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Abstract:

An optical antenna assembly including multiple optical antenna elements,
each of the optical antenna elements are arranged in a regular pattern
and carried by a supporting body. The regular pattern of the plurality of
optical antenna elements is nonuniform. Certain ones of the optical
antenna elements are configured to respond to the one or more waves of
light.

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86. An electromagnetically responsive apparatus, comprising:a. At least
one antenna element sized to interact with electromagnetic energy at at
least one optical frequency; andb. At least one nonlinear electrical
element integral to the antenna element.

87. The apparatus of claim 86 wherein the antenna element includes a
nanotube.

88. The apparatus of claim 87 wherein the nanotube includes a
discontinuity of a type that produces a nonlinear electrical response.

89. The apparatus of claim 88 wherein the discontinuity is a bend integral
to the nanotube.

90. The apparatus of claim 86 including electrical detection circuitry
responsive to a harmonic of the at least one optical frequency.

91. The apparatus of claim 86 wherein the apparatus includes at least a
plurality of antenna elements.

92. The apparatus of claim 91 wherein a first subset of the antenna
elements is responsive to a first optical frequency and a second subset
of the antenna elements different from the first subset and responsive to
a second optical frequency different from the first optical frequency.

93. The apparatus of claim 92 further including a third subset of the
antenna elements responsive to a third optical frequency different from
the first and second frequencies.

94. An optical detection structure comprising:An array of passive gain
elements responsive to electromagnetic energy at at least one optical
frequency, each of the passive gain elements including an integral
nonlinear device responsive to; andAt least one guide coupled to each of
the integral nonlinear devices and configured to guide electromagnetic
energy at a harmonic of the at least one optical frequency.

95. The optical detection apparatus of claim 94 wherein each of the
passive gain elements includes a monopole.

96. The optical detection apparatus of claim 94 wherein each of the
passive gain elements includes a nanotube.

97. The optical detection apparatus of claim 94 wherein each of the at
least one guides is configured to support plasmon propagation.

98. The optical detection apparatus of claim 94 wherein each of the at
least one guide is integral to the passive gain element.

99. The optical detection apparatus of claim 94 wherein the array includes
at least three passive gain elements arranged in a substantially
rectilinear pattern.

100. The optical detection apparatus of claim 94 wherein the array
includes at least three passive gain elements arranged along at least one
axis in a (sin x)/x distribution.

101. A method of detecting electromagnetic energy at optical frequencies,
comprising:Concentrating a plurality of selected portions of the
electromagnetic energy in a respective plurality of physical gain
structures; andProducing respective signals indicative of the selected
portions of the electromagnetic energy by frequency converting the
concentrated electromagnetic energy within the physical gain structures.

102. The method of claim 101 wherein frequency converting the concentrated
electromagnetic energy includes inducing a square law response.

103. The method of claim 101 further including processing the respective
produced signals to produce a signal indicative of the electromagnetic
energy at optical frequencies.

104. The method of claim 103 further including combining the respective
produced signals.

105. The method of claim 104 wherein combining the respective produced
signals precedes processing the respective produced signals.

106. The method of claim 101 further including combining each of the
respective produced signals with a phase reference signal.

107. The method of claim 101 wherein the phase reference signal is a
guided signal.

108. The method of claim 101 wherein the phase reference signal is a free
space signal.

109. The method of claim 101 wherein combining each of the respective
produced signals with the phase reference signal includes mixing each of
the respective produced signals with the phase reference signal within a
common device.

110. A method of producing optical gain, comprising:Receiving a portion of
an electromagnetic wave at an optical frequency with an antenna element;
andProducing a downconverted signal corresponding to the electromagnetic
wave within the antenna element.

111. The method of claim 110 wherein producing a downconverted signal
corresponding to the electromagnetic wave within the antenna element
includes producing a nonlinear response within the antenna element.

112. The method of claim 110 wherein producing a nonlinear response within
the antenna element includes producing an electromagnetic potential
across a region of the optical antenna element having a nonlinear
response to electric potentials.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]The present application is related to, claims the earliest available
effective filing date(s) from (e.g., claims earliest available priority
dates for other than provisional patent applications; claims benefits
under 35 USC §119(e) for provisional patent applications), and
incorporates by reference in its entirety all subject matter of the
following listed application(s) (the "Related Applications") to the
extent such subject matter is not inconsistent herewith; the present
application also claims the earliest available effective filing date(s)
from, and also incorporates by reference in its entirety all subject
matter of any and all parent, grandparent, great-grandparent, etc.
applications of the Related Application(s) to the extent such subject
matter is not inconsistent herewith. The United States Patent Office
(USPTO) has published a notice to the effect that the USPTO's computer
programs require that patent applicants reference both a serial number
and indicate whether an application is a continuation or continuation in
part. The present applicant entity has provided below a specific
reference to the application(s) from which priority is being claimed as
recited by statute. Applicant entity understands that the statute is
unambiguous in its specific reference language and does not require
either a serial number or any characterization such as "continuation" or
"continuation-in-part." Notwithstanding the foregoing, applicant entity
understands that the USPTO's computer programs have certain data entry
requirements, and hence applicant entity is designating the present
application as a continuation in part of its parent applications, but
expressly points out that such designations are not to be construed in
any way as any type of commentary and/or admission as to whether or not
the present application contains any new matter in addition to the matter
of its parent application(s).

[0007]The present application relates, in general, to antennas and related
components and systems, at or near, optical frequencies.

BRIEF DESCRIPTION OF THE FIGURES

[0008]FIG. 1 is a schematic diagram of one embodiment of an optical
antenna assembly that is configured to receive optical energy;

[0009]FIG. 2 is a schematic diagram of another embodiment of an optical
antenna assembly that is configured to emit light;

[0010]FIG. 3 is a generalized cross sectional diagram of a portion of one
embodiment of an optical antenna assembly;

[0011]FIG. 4 is a perspective view of a portion of another embodiment of
an optical antenna assembly;

[0012]FIG. 5a is an isometric representation of a portion of another
embodiment of an optical antenna assembly that is produced with
nanotubes;

[0013]FIG. 5b is a top view of one of the optical antenna elements of the
optical antenna assembly that is shown in FIG. 5a;

[0014]FIG. 6 is a view of one embodiment of an interference pattern
created by a plurality of optical antenna elements;

[0015]FIG. 7 is a view of another embodiment of an interference pattern
created by the plurality of optical antenna elements of FIG. 6, in which
that relative phase of one of the optical antenna elements is shifted;

[0016]FIG. 8 is a side view of one embodiment of the optical antenna
element and an associated detector, in which the detector is configured
as a diode;

[0017]FIG. 9 is a side view of another embodiment of the optical antenna
element and an associated detector, in which the detector is configured
as a transistor;

[0018]FIG. 10 is a side view of yet another embodiment of the optical
antenna element and an associated detector, in which the detector is
configured as a Schottky diode;

[0019]FIG. 11 is a general schematic view of one embodiment of an
oscillator circuit that can be used to produce a signal;

[0030]FIG. 22 is a diagrammatic representation of one embodiment of
optical antenna element arrangements; and

[0031]FIG. 23 is a schematic diagram of one embodiment of an arrangement
of optical antenna elements according to grid.

DETAILED DESCRIPTION

[0032]This disclosure describes a number of embodiments of one or more
optical antenna elements that can be arranged in an optical antenna
assembly. The optical antenna assembly may include an array of the
optical antenna elements. Such arrays of optical antenna elements may, in
certain embodiments, be spatially arranged in either a non-uniform or
uniform pattern to provide the desired optical antenna assembly
characteristics and/or generate or receive light having a desired
response. The configuration of the arrays of optical antenna elements
within the optical antenna assembly may affect the shape, strength,
operation, and characteristics of the waveform received by, or generated
by, the optical antenna assembly.

[0033]Optical antenna elements may be configured to either generate or
receive light. In actuality, the physical structure of a generating
optical antenna element can be identical to that of a receiving optical
antenna element. As such, a single optical antenna element, or an array
of such elements, can be used to generate and/or receive light. This
disclosure thereby includes a description of the structure or the
associated characteristics of a number of embodiments of generating and
receiving optical antenna assemblies. The receiving optical antenna
assembly, as described with respect to FIG. 1, acts to convert received
light (of the visible or near-visible spectrum) into an electrical
signal. The generating optical antenna element, as described with respect
to FIG. 2, converts an electrical signal into corresponding generated
light.

[0034]Within this disclosure, the term "optical" as applied to the phrase
"optical antenna" indicates that the antenna generates or receives
energy, or otherwise interacts with energy, at or near optical
frequencies. This light and/or energy can be converted to/from electrical
signals that can be transported along conductive or similar pathways. The
fundamental physics of such optical antenna elements can therefore rely
upon the conversion of energy between electromagnetic waves that travel
through a medium such as air or a vacuum, and electrical signals that
travel along an electrically conductive or similar pathway, and/or vice
versa. A number of publications that relate to nanostructures are
described in the publication: "NANO-OPTICS Publications 1997-2005";
printed on Dec. 22, 2004; pp. 1-7; Nanooptics Publications; located at:
http://nanooptics.uni-graz.at/ol/ol_publi.html.

[0036]In this disclosure, the terms "visible" or "optical" light, or
simply "light" also relate in this disclosure to so-called "near-visible"
light such as that in the near infrared, infra-red, far infrared and the
near and far ultra-violet spectrums. Moreover, many principles herein may
be extended to many spectra of electromagnetic radiation where the
processing, electronic components, or other factors do not preclude
operation at such frequencies, including frequencies that may be outside
ranges typically considered to be optical frequencies.

[0037]Within this disclosure, the term "regular", when referring to a
plurality or array of optical antenna elements, is not limited to
substantially evenly spacing between or among various components.
Moreover, regular spacing may be satisfied at the points of attachment,
or other locations of components, that may not extend in parallel.
Further, the dimensions of individual components may be small in many
embodiments, and minor deviations from exact placement or separation may
still be considered regular. Further, regular may pertain to spacings,
features, separations, or other aspects of individual or groups of
components.

[0038]Similarly, the term "uniform", does not require exact uniformity of
size, features, spacing, distribution or other aspects that may be
considered to be uniform. Altering a configuration of optical antenna
elements by reducing the probability of optical antenna elements forming
thereat, forming shorter optical antenna elements in a particular region,
removing optical antenna elements from a particular region, etc. can have
the effect of altering the optical characteristics of the of the optical
antenna assembly.

[0039]To efficiently generate or receive light, the effective lengths of
the optical antenna elements usually equal some integer multiple of
quarter wavelengths of the generated or received light (λ/4). The
physical length dimension of single wavelength versions of the optical
antenna elements can approximately equal the effective wavelength of the
generated or received light. Due to the minute wavelength of many of the
relevant ranges of light, many embodiments of the optical antenna
elements can be fabricated to be minute (e.g. such as within the micro-
or nano-scale), and still allowing the antenna elements to couple with
the electromagnetic radiation that occurs at similar light wavelengths
such as within the visible spectrum.

[0040]In some cases, optical antenna assemblies (including both those that
are configured to receive light and/or generate light) can be designed to
provide a variety of efficiencies based largely on coherency of light
produced by multiple included optical antenna elements and their
coherencies. Light from multiple coherently generating or receiving
optical antenna elements may be in phase at a number of locations or at
various angular ranges. In such configurations, their wave amplitude may
add or interfere coherently at one or more locations or angles relative
to the array of optical antenna element. In other applications, it may be
desirable to configure an optical antenna assembly to generate light that
is out of phase at one or more spatial locations or angular ranges
relative to the optical antenna assembly, and therefore generate or
receive substantially incoherent light or partially coherent light at
some or all spatial locations or angular ranges relative to the array.

[0041]The relationship between two adjacent optical antenna elements such
as exists in an antenna array is described herein to indicate how the
light from arrays of optical antenna elements constructively or
destructively interfere. This constructive and destructive interference
is often relevant to such optical antenna assembly issues as wave phases,
beamforming, and beamsteering as described in this disclosure. The
relationship between the two adjacent optical antenna elements can be
extended in principle to either uniform or non-uniform arrays depending
upon the desired waveform. Moreover, while such principles can be
relevant to the operation, understanding, and/or characteristics of many
embodiments, a variety of other design principles may be employed in such
designs or analyses.

[0042]Light that is generated or received from pairs of proximally-located
generating optical antenna elements or proximally-located receiving
optical antenna elements can destructively interfere at a number of
locations relative to the optical antenna elements, and light can
constructively interfere at other spatial locations. As such, the
respective generating or receiving optical antenna elements can generate
or receive light from one or more spatial locations or angular ranges.
The relative phase relationships of the light that is generated or
received by the optical antenna element largely dictates those spatial
locations, relative to the array, where the combined optical signal is
mostly in phase and therefore the amplitude of the combined signals from
the array of optical antenna elements contribute to be of the greatest
intensity at each point along that region of the waveform. Destructive
interference between proximate pairs of optical antenna elements can
produce a reduced amplitude or gain in corresponding regions.

[0043]Adjusting the relative phases of the generating or receiving optical
antenna elements can control gain along respective paths relative to the
optical antenna assembly at which the light is generated or received. In
some applications the phases may be controlled to produce a relatively
high gain along a limited range of directions. In an emissive case, this
process may be referred to as "beamforming". An associated process
involves changing the direction of gain. This process may be referred to
as "beam steering". Many embodiments of the optical antenna assembly can
be phased array optical devices that utilize beamforming and/or
beamsteering techniques.

[0044]In many embodiments, an optical antenna assembly 100 as described
with respect to both FIGS. 1 and 2, includes a number of the optical
antenna elements 102 that can be arranged in a substantially planar array
to form the optical antenna assembly 100, though the structures methods
and systems described herein are not limited to embodiments having planar
or substantially planar arrangements. The arrangement of optical antenna
elements 102 can be either regular or non-regular and can be
two-dimensional, or three-dimensional. In one approach, a three
dimensional arrangement may be achieved by stacking two or more
two-dimensional arrays. The arrangements of antenna elements and the
configuration of individual optical antenna elements may be varied
according to the principles described herein to produce a variety of
frequency responses, beam patterns, or other operational properties.

Examples of Receiving Optical Antenna Assemblies

[0045]This portion of the disclosure describes a number of embodiments of
a receiving optical antenna assembly as described with respect to FIG. 1.
A subsequent portion of the disclosure describes a number of embodiments
of a generating optical antenna assembly, as described with respect to
FIG. 2. Several embodiments of optical antenna assemblies, including
embodiments according to FIGS. 1 and 2, can be arranged in either a
receiving or generating configuration, as described with respect to FIGS.
1, 2, 3, 4, 5a, or 5b. The relevance of having the arrays of optical
antenna elements uniformly or non-uniformly spaced within the optical
antenna assemblies is described in this disclosure. Certain embodiments
of the detector and light source configurations, by which light
transitions to, or is transitioned from, electrical signals are also
described herein.

[0046]The optical antenna assembly 100 that is configured as a receiver
can be applied to a number of different applications including, but not
limited to, a light detector, a light sensor, a camera, etc. The optical
antenna assembly 100 that is configured as a receiver includes a
plurality of optical antenna elements 102 that can be each individually
coupled to a respective phase adjust ("φ-adjust") 104 via a
respective guiding structure, represented as an individual electrical
conductor 105. Electrical signals can transit along the guiding structure
from the φ-adjust 104 to a combiner 106.

[0047]One skilled in the art will recognize that a variety of approaches
to guiding structures may be appropriate to carry signals to or from the
antenna elements 102. One example of a nanoparticle waveguide is
described in the article J. R. Krenn; "Nanoparticle Waveguides Watching
Energy Transfer"; News & Views; April 2003; pp. 1-2; Volume 2; Nature
Materials, incorporated herein by reference. An example of a technique to
"squeeze" millimeter waves into a micron waveguide is described in the
article: A. P. Hibbins, J. R. Sambles; "Squeezing Millimeter Waves into
Microns"; Physical Review Letters; Apr. 9, 2004; pp. 143904-1/143904-4;
Volume 92, Number 14; The American Physical Society, incorporated herein
by reference. Additional references described and incorporated
hereinbelow analyze and characterize the propagation of energy along
various guiding structures, such as conductors, at higher frequencies,
including those at or near optical frequencies and those relating to
propagation of plasmons along guiding structures. Some such pathways may
include conductors, may be formed from semiconductive or dielectric
materials, or may include a combination thereof. Moreover, materials that
may be characterized as dielectrics or conductors at one frequency may
operate very differently at other frequencies. The actual material that
carries or guides electrical signals or waves will depend upon a variety
of factors, including the frequency of the energy propagating.
Nevertheless, for clarity of the presentation for the current portion of
this description, the various guiding structures are represented
diagrammatically and referred to herein as the electrical conductor 105,
though the term conductor should not be considered to be limited to
materials typically considered to be electrical conductors at relatively
low frequencies.

[0048]The φ-adjust 104 for each light-receiving optical antenna
element 102 is capable of adjusting the relative phase of the electrical
signal relative to light that is received as a signal formed by each
particular optical antenna element 102 at the combiner 106. The
φ-adjusts 104 are presented diagrammatically in FIGS. 1 and 2 for
clarity of presentation. One skilled in the art will recognize that a
variety of structures may be implement the φ-adjust 104
functionality, including, in a relatively straightforward implementation,
waveguides having materials with fixed or electrically controllable
effective dielectric constants and/or optical transmission distances.
Other various exemplary embodiments of the φ-adjust 104 will be
described in more detail hereinbelow.

[0049]In one approach, the φ-adjust 104 controls the effective time
required for a signal to travel from the particular optical antenna
element 102 to the combiner 106, and therefore the relative phase of a
signal carried by the electrical conductor 105. By adjusting the relative
phase of signal traveling through each of the multiple φ-adjusts 104,
the relative phases of the signals that can be applied from the optical
antenna elements 102 to the combiner can be adjusted.

[0050]In one embodiment, signals output from each φ-adjust 104 arrive
at the combiner 106 for each receiving optical antenna assembly 100. One
φ-adjust 104 is associated with each light-receiving optical antenna
element 102, and the φ-adjust 104 is configured to adjust the
relative phase of light being produced or received by functioning as a
fixed or variable delay element. It is thereby envisioned that in one
embodiment, each φ-adjust 104 can be configured as a signal-delay
component that delays the duration required for a signal to pass through
the φ-adjust 104 by some percentage of a wavelength of the light that
is to be received or generated by other corresponding optical antenna
elements 102, thereby alternating the relative phases of the signals
produced by the different optical antenna elements.

[0051]The embodiments of the receiving optical antenna assembly 100 as
described with respect to FIG. 1 include the combiner 106 that mixes or
otherwise combines signals from the different optical antenna elements to
provide an output signal (not shown) corresponding to the amount of light
energy received at the respective optical wavelength of each optical
antenna element 102.

[0052]While the combiner 106 is presented diagrammatically as an
operational block coupled to the φ-adjusts 104, one skilled in the
art will recognize that a variety of configurations may achieve the
functionality realized by the combiner. Some such configurations may even
employ free-space optical or RF (radio frequency) techniques to produce a
signal that is a function of the signals from the φ-adjusts 104. In
some configurations, the signal may be a combination of the signals from
the φ-adjusts 104 or may be a nonlinear, square law or other function
of such signals, such as a down converted, square law combination, phase
or frequency modulated version, or even an integrated sum of such
signals.

[0053]In some embodiments, the combiner 106 can be configured to include
an adder circuit, a multiplier circuit, a mixer circuit, or some other
arithmetic configuration depending upon the functionality of the optical
antenna assembly 100. The combiner can also include a signal amplifier
that amplifies the signal strength that is applied to the combiner 106 to
a level (e.g., for certain prescribed frequencies) that is sufficient to
transmit the signal to another device, or to an image processor that may
identify information represented by the various signals. In many
embodiments, the combiner 106 can be associated with, or integrated into,
a computer device such as a signal processing portion of an analog or
digital computer. As such, the computer device functions as a signal
processor to analyze, evaluate, store, or otherwise process signals
corresponding to the light received from the different optical antenna
elements 102.

[0054]In different embodiments, a computer device can be integrated with
the combiner 106, and in certain embodiments the computer device can be
configured as a full-sized general purpose computer such as a personal
computer (PC), a laptop, or a networked computing device. In alternate
embodiments, the computer device that is included as portion of the
combiner 106 can be configured as a microprocessor, a microcomputer, an
application-specific integrated circuit (ASIC), a devoted analog or
digital circuit, or other such device. The computer device can therefore
be configured as a general-purpose computer, a special-purpose computer,
or any other type of computer that is configured to deal with the
specific task at hand. In certain embodiments, the combiner 106 includes
a multiplexer and/or a downconverter that combines one or more aspects of
signals from a plurality of optical antenna elements 102 or a plurality
of sets of optical antenna elements 102. While the combiner 106
downconverter is presented diagrammatically herein, a number of
structures or materials can operate as combiners, multiplexers, or
downconverters, typically through a nonlinear or linear mixing of
signals.

[0056]The one or more aspects of the signals can be characterized by a
plurality of frequency ranges, a plurality of time samples, or a
plurality of other separable or distinguishable features for the signals
that originate from pluralities of optical antenna elements into a single
signal that can be transmitted to a remote location for processing, or
alternatively the processing can be performed in situ. The output from
the combiner 106 can be transferred to a remote location, such as would
occur if the optical antenna assembly 100 is configured as part of a
network. In certain embodiments of the optical antenna assembly, a
variety of components can be operably coupled downstream or upstream of
the combiner 106 to assist in the handling or transmission of data
signals produced by the combiner.

[0057]Another embodiment of a downconverter includes an optical
down-converter that, like other forms of downconverters, decreases the
frequency of signals. One example of an optical downconverter is an
optical device that mixes the signal to be downconverted with a second
optical signal, as may be generated by an associated oscillator 107.
Mixing of optical signals to produce a lower frequency indicator of
information carried by one or more signals is known. An example of such
mixing in polymer based materials is described in Yacoubian, et al, E-O
Polymer Based Integrated Optical Acoustic Spectrum Analyzer, IEEE Journal
of Selected Topics in Quantum Electronics, Vol. 6, No. 5
September/October 2000.

[0058]Other examples of optical downconversion using heterodyning or
homodyning are described by Yao in Phase-to-Amplitude Modulation
Conversion Using Brillouin Selective Side Band Amplification, IEEE
Photonics Technology Letters, Vol. 10. No. 2, February 1998;
Hossein-Zadeh and Levi, Presentation at CLEO 2004, May 19, 2004, entitled
Self-Homodyne RF-Optical Microdisk Receiver, each of which is
incorporated herein by reference. Other approaches to downconversion
and/or detection are described later in this description.

[0059]While the downconverter is shown as incorporated into the combiner,
the down-converter may be interposed between the optical antenna elements
102 and the φ-adjusts 104, may be interposed between the
φ-adjusts 104 and the combiner 106, or may itself include the
φ-adjusts 104. In certain embodiments, the down-converter can be
operably coupled to the combiner, wherein the frequency of the
electromagnetic radiation that is applied to the combiner 106 is reduced
to a level that can be propagated along electrical conductor. In other
embodiments, it is envisioned that a mixer may be applied downstream of
the combiner 106.

[0060]Returning to a general description of the embodiment illustrated in
FIG. 1, a wavefront 120 indicates a generally planar orientation of light
waves arriving at, and/or received by, the respective receiving optical
antenna assembly 100. While the incoming wave in this description is
presented as planar for clarity of presentation, the embodiments herein
may be configured for operation with a variety of input wave formats,
including non-coherent waves and non-planar waves. Moreover, in the
disclosure, the term "planar" as applied to waveforms is not limited to
the strictest definitions of planar and may include any substantially
planar surface, including those that do not have infinite radii of
curvature or those that may, for example, have slight surface
irregularities. For the receiving optical antenna assembly 100, the
wavefront 120 is illustrated as moving in a downward direction as
indicated by the arrow 124.

[0061]The receiving optical antenna assembly 100 converts the light energy
of the wavefront 120 to electrical energy that travels along an
electrically conductive path or other signal transmissive path. The
receiving optical antenna assembly 100 can thereby be considered as an
optical transducer that converts received light energy into a different
form.

[0062]By adjusting the relative delays of the different optical antenna
elements using the φ-adjusts 104, the sensitivity, directionality,
gain, or other aspects of the optical antenna assembly 100 can be
controllably varied. In certain generating embodiments, this can provide
a beamforming and/or beamsteering function.

[0063]In one approach, the φ-adjusts 104 may also be configured to
selectively block or diminish signals from their respective optical
antenna element, as will be described below. Therefore, in certain
embodiments, the φ-adjusts 104 can functionally alter the
light-generating or light-receiving effects of a particular optical
antenna element 102. Removing (or decoupling) certain optical antenna
elements from certain arrays of optical antenna elements can make an
otherwise regularly-spaced array more non-regularly spaced or more
sparse. Alternatively, removing selected elements can functionally
control the gain of the optical antenna assembly along selected paths,
vary the width of the center lobe and/or the side lobes, or alter some
other characteristics that may be dependent upon frequency. Design
considerations relating to the number, position, spacing, and other
aspects of the optical antenna elements will be described hereinbelow.

[0064]In many embodiments of the receiving optical antenna assembly 100 as
described with respect to FIG. 1, each of the optical antenna elements
102 can be configured to receive signals that vary in amplitude or phase
at different spatial directions across the array. Examples include, but
are not limited to, a telescope, a camera, an image detector, a receiving
portion of a facsimile machine, a communications receiver, an image
copier, or the like.

[0065]Other embodiments of the receiving optical antenna assembly can be
arranged to receive a substantially uniform image across the entire face
of the display. Examples of these embodiments include, but are not
limited to, motion detectors, presence detectors, time of day detectors,
timing detectors associated with sports events, or the like. The
particular configuration of the various components, such as the combiner,
can be designed to take into account the type of waveform images that can
be received by the optical antenna assembly 100, as well as the
uniformity of the waveform image.

[0066]It is envisioned that any configuration of such optical antenna
assemblies that produces an electrical signal responsive to received
light, as claimed by the claims herein, may be within the intended scope
of the receiving optical antenna assembly.

Examples of Signal Generating Optical Antenna Elements

[0067]FIG. 2 shows a schematic diagram of one embodiment of a generating
optical antenna assembly 100 that is configured to emit either coherent
light energy or incoherent light energy. Many of the components and
techniques that are described in this disclosure with respect to
receiving optical antenna assemblies also apply to the generating optical
antenna assemblies, and vice versa. Different embodiments of the
generating optical antenna assembly 100 can be used in a variety of
applications that include, but are not limited to a light source, a
display, and/or a variety of other applications that involve directing
light toward spatial-locations relative to that array.

[0068]In this disclosure, the receiving and generating embodiments of the
optical antenna assembly 100 can be provided with many identical
reference characters since many of the components of both configurations
may be identical or similar, and in some cases, both configurations may
actually be used interchangeably. However, certain components of the
generating optical antenna assembly may be configured differently for the
remaining optical antenna assembly (e.g., such as having differing
circuitry and/or different biasing) to provide for different operational
characteristics.

[0069]While one embodiment of the optical antenna assembly 100 may be
configured to generate coherent radiation at certain locations similarly
to laser or holographic devices, other embodiments of the optical antenna
assembly may produce incoherent light. Such a light source could be
steerable and controllable to produce coherent or incoherent light at
different times and or different spatial locations or along selected
paths. In certain embodiments of the optical antenna assembly 100, the
plurality of optical antenna elements 102 included within the generating
optical antenna assembly 100 can be arranged in an array. In other
embodiments, the optical antenna assembly 100 may include one, or a
number of, discrete optical antenna elements 102. Each optical antenna
element 102 can be individually attached or operably coupled via a
distinct φ-adjust 104.

[0070]The embodiment of the generating optical antenna assembly 100, as
described with respect to FIG. 2, includes the one or more optical
antenna elements 102, corresponding φ-adjusts 104, the electrical
conductors 105, and signal splitter 205. The signal splitter 205
diagrammatically represents a component or set of components that
distribute signals among the various optical antenna elements 102.
However, one skilled in the art will recognize that the signal splitter
205 may actually include functions such as signal combining in some
embodiments. For example, as described for some embodiments herein, and
as represented in FIG. 2, the signal splitter 205 may combine selected
signals with signals from an associated oscillator 206.

[0071]In one embodiment, the signal splitter 205 outputs an electrical
signal that is a combination of an information signal and the signal from
the oscillator 206. The output signal travels along the electrical
conductor 105 to the φ-adjust 104. The φ-adjust 104 produces a
phase adjusted version of the signal to drive the respective optical
antenna element 102. The output of the optical antenna element 102 thus
corresponds to the information signal and the oscillator signal.

[0072]Depending upon the embodiment of the generating optical antenna
assembly 100, a varying, or consistent, level of illumination can be
created across all of the optical antenna elements 102 within the optical
antenna assembly 100. For example, if the optical antenna assembly 100 is
configured as a light source, then each of the optical antenna elements
102 may generate relatively broadband light at its respective spatial
location. In other light source approaches the optical antenna elements
102 may be matched to selectively produce light in one or more narrow
bands or one or more substantially discrete frequencies. Where the light
is in one or more narrow bands, the optical antenna elements 102 may be
sufficiently matched to generate coherent light energy.

[0073]In certain display device embodiments, it may be desirable to
provide a varying light configuration across the optical antenna assembly
100 to display an image by varying the amplitude and/or phase of light
from respective ones or sets of optical antenna elements 102.

[0074]If the optical antenna assembly 100 is configured as an optical
display, then the intensity of the signal from each of the optical
antenna elements 102 may be controlled on an individual element basis or
according to groupings of elements to provide controllable illumination
at respective spatial locations. Where the pattern of the illumination
matches a selected image, the emitted light energy may produce a viewable
display. In some approaches, the optical antenna elements 102 may be
configured to emit light at one or more visible wavelengths so that
viewable image may be directly viewable or viewable on an image surface,
such as a screen or diffuser. In other approaches, the emitted light may
be at frequencies not directly viewable by humans and converted to
visible light through wavelength conversion. In one simple approach to
wavelength conversion, the emitted light strikes a phosphor, which may be
upconverting or downconverting depending upon the configuration, and the
phosphor emits visible light with an energy level corresponding to the to
level of the emitted non-visible light.

[0075]Where the light emitted by the optical antenna elements 102 is
coherent, the gain may be controlled as described herein to directionally
control beam gain, to produce a scanning beam display.

[0076]As described with respect to the FIG. 1 receiving configuration of
the optical antenna assembly, the φ-adjusts 104 effectively adjust
the relative transit time for a signal (in either direction) between the
respective optical antenna element 102 and the corresponding signal
splitter 205. In the generating configuration of the optical antenna
assembly 100, the φ-adjust 104 can thereby alter the relative phase
of the light that is generated by the respective generating optical
antenna elements. Such phase control may allow the generating optical
antenna assembly 100 to act as a beamsteerer and/or beamformer to control
the directionality or angular gain relative to the array of optical
antenna elements 102.

[0077]In the embodiment of the optical antenna assembly 100 as described
with respect to FIG. 2, the oscillator 206 generates an electrical or
optical signal that can be supplied to the respective optical antenna
element 102. If the signal that is generated from the oscillator 206 is
an electrical signal, the signal may directly drive the optical antenna
element 102 or the frequency may be lower than that to be emitted by the
optical antenna element 102. In such configurations, an up-converter, as
will be described below, can convert the frequency of the electrical
signal into the frequency of the light from each optical antenna element.
Signals output from each oscillator 206 can therefore be applied to one
or more respective φ-adjusts 104 that are associated with each
generating optical antenna assembly 100. Each φ-adjust 104 may then
adjust the relative phase of the light to be generated by each respective
optical antenna element 102. As such, each φ-adjust 104 acts as a
variable delay element for signals applied to the optical antenna element
102.

[0078]The signal splitter 205 is shown in FIG. 2 as being associated with
the oscillator 206. Some embodiments of the optical antenna assembly 100
use an oscillator 206 to generate a signal, that may be sinusoidal, of a
particular frequency that may then form a reference or carrier signal.
The oscillator 206 can be configured in a number of different
embodiments, as described below with respect to FIGS. 11, 12, and 13. It
is emphasized that the different embodiments of the oscillator as
described in this disclosure are illustrative in nature, and are not
intended to be limiting in scope. As such, other embodiments of
oscillators can be considered to be within the intended scope of the
present disclosure.

[0079]In certain light-generating embodiments such as a light source, a
single oscillator 206 can generate a signal, which may be sinusoidal,
that can be applied to individual, multiple, or all of the optical
antenna elements 102 within the optical antenna assembly 100. In
alternate embodiments such as a display, each of the array of display
picture elements (pixels) may be defined by one or more optical antenna
elements 102, such that each of (or each group of) the optical antenna
elements 102 is associated with a distinct oscillator 206. If
substantially uniform levels of illumination are to be provided across
multiple optical antenna elements, then fewer oscillators 206 that each
supply a consistent signal to multiple optical antenna elements may be
used.

[0080]In those embodiments of the generating optical antenna assembly 100
that distribute a substantially uniform levels of light across an entire
array (such as where the generating optical antenna assembly 100 is used
as a light source), the signal splitter 205 can be configured with one
oscillator circuit which applies an identical input signal to each of the
generating optical antenna elements 102.

[0081]As noted previously, in some approaches the signal splitter 205 is
functionally configured to split an input signal, such as the information
signal into two or more output signals that may be identical. Each of the
output signals drive a respective generating optical antenna element 102
or may form a carrier signal that may be combined with another signal
(such as a signal from the oscillator 206) to drive the respective
optical antenna element 102.

[0082]Such an embodiment may still employ φ-adjusts 104. In one
approach, each φ-adjust 104 adjusts the time for the oscillator's
signal to reach the corresponding optical antenna element 102, and
therefore the relative phase of that optical antenna element. The
φ-adjusts 104 in the generating configuration of their respective
optical antenna elements 102 and thereby alter the phase of the light
generated across the array of elements within the optical antenna
assembly 100. Such phase control can employ known techniques to control
the effective direction of emitted energy for localized or directional
illumination.

[0083]Certain embodiments of the generating optical antenna assembly 100
may include an up-converter that is associated with the signal splitter
205. The up-converter acts to transition light to the frequency of a
received electrical signal, such as may be modulated according to
information content into a signal at optical frequencies. Such an
up-converter is typically a non-linear, square law or similar device that
produces an output that is a function of the information bearing signal
and a second signal, such as may be provided by the oscillator 206. An
example of a non-active form of up-converter can be found in T. J. Yen,
W. J. Padilla, N. Fang, D. C. Vier, D. R. Smith, J. B. Pendry, D. N.
Basov, X. Zhang; "Terahertz Magnetic Response from Artificial Materials";
Science Magazine Reports; Mar. 5, 2004; pp. 1494-1496; Volume 303; which
is incorporated herein by reference.

[0084]Other embodiments of the generating optical antenna assembly 100
include an oscillator that generates signals at optical frequencies
directly, thereby bypassing the need for a separate up-converter.

[0085]It is also envisioned in certain embodiments that a mixer circuit,
multiplier, nonlinear circuit, or other suitable frequency conversion
configuration, can up-convert or downconvert the frequency of the
electrical signal that is to be transmitted or received by the signal
combiner 205 from optical frequencies to frequencies that may be handled
more easily by conventional circuitry. An example of a device that
generates harmonics of an input signal is described in the article: S.
Takahashi, A. V. Zayats; "Near-field second-harmonic generation at a
metal tip apex"; Applied Physics Letters; May 13, 2002; pp. 3479-3481;
Volume 80, Number 19; American Institute of Physics, incorporated herein
by reference.

[0086]It is envisioned that any configuration of optical antenna assembly
that generates light in response to a received electrical signal, as
claimed by the claims, may be within the intended scope of the generating
optical antenna assembly.

Examples of Optical Antenna Assembly Fabrication Techniques

[0087]Many embodiments of the optical antenna elements 102 can be minute
(in the micro- or nano-scale), since they can have similar physical
dimensions to integer multiples or divisors of the wavelength, λ,
of the light with which the optical antenna elements couple (e.g.,
λ, λ/2, or λ/4). As such, each receiving or generating
optical antenna element 102, as described with respect to the respective
FIGS. 1 or 2, is configured to respectively receive light or generate
light within the visible as well is near-visible light spectrum.
Typically, visible wavelengths are on the order of 400-700 nm. In many
cases, near visible wavelengths can be considered to be from about 300 nm
up to about 1,900 nm. However, other optical ranges may be applicable.
For example, the principles and structures described herein may be
extended in some cases to substantially shorter wavelengths, such as
those of known photolithographic techniques. Such wavelengths can be
currently on the order of a few tens of nanometers, e.g., 40 nm, although
future production techniques can be expected to reduce these to the
single nanometer ranges, or even smaller. The principles herein should be
adaptable to such dimensions, taking nanoscale effects into account.
Similarly, the upper wavelength (lower frequency) limits are not
necessarily limited to visible or near visible wavelengths. In fact, the
principles, structures, and methods herein may be applicable at
wavelengths in the near infrared (e.g., about 700-5000 nm), mid-infrared
(e.g., about 5000 nm-25 micron), or far infrared (e.g., about 25-350
micron ranges). One skilled in the art will recognize that these ranges
are approximate. For example, the upper end of the mid-infrared range is
sometimes defined as about 30 or 40 microns and the upper end of the far
infrared is sometimes defined as about 250 microns.

[0088]A quarter-wave optical antenna element 102 has an effective length
substantially equal to one-quarter the wavelength of the
received/generated light for the corresponding medium. A half-wave
optical antenna element 102 has an effective length substantially equal
to one-half the wavelength of the received/generated light, for the
corresponding medium. One skilled in the art will recognize that the
wavelength depends upon the configuration and associated media, including
the effective dielectric constant of the media through which the signals
propagate.

[0089]The individual optical antenna elements 102 can be arranged in
arrays to form the optical antenna assemblies, and hence the optical
antenna elements may be fabricated within the nano- or micro-scale. It is
therefore envisioned that many optical antenna assembly applications will
involve a large number of the optical antenna elements that can be
arranged in an array. As such, one fabrication approach employs
semiconductor processing techniques to produce a number of elements
having well controlled positioning and/or dimensions.

[0090]Such fabrication approaches may be selected in cases where there are
little operation and configuration variations between the individual
optical antenna elements, though other systems may also employ such
techniques.

[0091]Appropriate semiconductor processing techniques include, but are not
limited to, lithography (such as photo-lithography, e-beam lithography),
nanotube growth, self assembly, or fabrication of other nano structures.
Other known techniques that can be used to produce large arrays of
optical antenna elements can be within the intended scope of the present
disclosure.

[0092]The different embodiments of the optical antenna assembly 100 can
therefore be considered as an optical antenna that "captures" or
"generates" light energy, as described respectively with respect to FIGS.
1 and 2. As may be noted from the above description, phase control of the
individual optical antenna elements may allow the gain of the optical
antenna assembly to be defined independently of conventional optical
focusing or processing techniques, such as with lenses, or of
diffractive, refractive, or reflective elements, including left handed
materials. However, the principles, structures, and methods described
herein do not necessarily exclude use with more conventional optical
focusing, shaping, processing or other techniques, such as lenses,
diffractive elements, phase plates, filters, apertures, polarizers, or
other more conventional components or systems.

[0093]Typical analysis of photon emitters or receivers traditionally has
been considered under the domain of quantum physics, as often
characterized by Schroedinger's equations. While such analysis may be
applicable to many aspects of the devices and systems described herein,
the design and characteristics of the optical antenna assembly 100 will
typically involve more Maxwellian analysis and design. As such, many of
the antenna techniques and equations that apply to antenna design, wave
propagation, coupling, and other aspects of the microwave, and other,
electromagnetic radiation spectra may be applied relatively directly to
the designs and systems described herein. For example, optical antenna
assembly designs, concepts and analysis may use phased-array techniques
for synthetic apertures or other antenna-related concepts to detect,
generate, direct, or otherwise interact with energy at optical
frequencies.

[0094]FIG. 3 shows diagrammatically a side view of one generalized
embodiment of the optical antenna assembly 100 as described with respect
to FIGS. 1 and/or 2. The optical antenna assembly 100 can be fabricated
using a variety of semiconductor processing techniques or other suitable
techniques. In certain embodiments, the substrate 202 or supporting body
carries such elements as the φ-adjust 104, the combiner 106, the
signal splitter 205, or the oscillator 206 as described in either FIG. 1
or FIG. 2, though these are omitted from FIG. 3 for directness of
presentation. In this disclosure, the term "carries" in the physical,
rather than signal carrying, context may apply to a component, such as
the optical antenna element, being individually attached or operably
coupled to the substrate 202, integrated into or contained within the
substrate, operably coupled to some intermediate structure that attaches
the optical antenna element to the substrate, or any other type of
arrangement where the substrate can be said to carry or support.
Additionally, in certain embodiments, the substrate 202 can be configured
considerably differently than conventional semiconductor substrates. For
example, materials such as polymers, metals, rubber, glasses, or minerals
can form the substrate that carries the optical antenna elements.
Additionally, in certain embodiments, some type of field can be
established to maintain the optical antenna element in position with
respect to each other in addition to or independent of physical
structural support.

[0095]The substrate may also include additional components in some
configurations, such as up-converters, down-converters, mixers, and/or
de-mixers that are described with respect to certain of the figures). A
row of optical antenna elements 102 may be positioned behind or beside
each optical antenna element 102 shown in FIG. 3, thereby creating a
two-dimensional array of optical antenna elements 102.

[0096]Where the elements 102 can be positioned in a relatively stacked
arrangement, multiple substrates, or one or more layers formed on
substrates that each contain a two-dimensional array of optical antenna
elements can be positioned in fixed or variable positions relative to
each other. In some cases, the two dimensional arrangements can be
accomplished by variable spacing between the rows of optical antenna
elements 102 or other non-uniform arrangements. Such two dimensional
arrangements may be stacked, deposited, formed or otherwise assembled or
fabricated with a stacked, layered, or other three dimensional
arrangement to form a three-dimensional array of optical antenna
elements. Such three-dimensional arrays can be used for a variety of
purposes, for example as a group of cooperating optical antenna elements.

[0097]In other applications, one or more of the layers of optical antenna
elements may operate as a reference waveform generator. The reference
wave may provide a driving signal for down converting or mixing, may
operate as a relative phase control, or may provide a reference wave
against which incoming or outgoing waves can be compared. In one
approach, the energy of the reference wave may be applied simultaneously
with that of an incoming wave to produce an electrical signal that
corresponds to a linear or nonlinear combination of the incoming and
reference waves. In one relatively straightforward approach, the
electrical signal corresponds to the sum of the amplitudes of the
reference wave and the incoming wave. If the two waves are at
substantially the same frequency, the sum may be a coherent sum and
provide relative phase information.

[0098]A variety of arrays of non-regular or regular optical antenna
element configurations can be described with respect to this disclosure.
In one embodiment, spacing between each row and/or column of optical
antenna elements 102 is relatively uniform to produce regular arrays of
optical antenna elements 102. Alternatively, each one of the optical
antenna elements may be irregularly spaced to produce relatively
non-uniform arrays of optical antenna elements. A variety of regular or
irregular arrays of optical antenna elements can be selected depending
upon the desired antenna gain and beam pattern. Where the relative phases
of incoming or outgoing waves can be determined or controlled, the gain
or directionality of the optical antenna assembly can be controlled using
beamforming and beamsteering concepts. The design, material, or the
configuration of the optical antenna elements may be selected based upon
the particular design or application of the array of the optical antenna
element.

[0099]In one embodiment, lithographical approaches can produce a large
number of different embodiments of arrays of optical antenna elements
102, or discrete optical antenna elements. The complexity of each optical
antenna element ranges from relatively simple dipole optical antenna
element configurations, including for example, nanotubes or conductive or
dielectric pillars, to those including bends, curves, discontinuities, or
other irregular configurations. Lithographic techniques can be used to
pattern the optical antenna elements or other parts of the optical
antenna assembly into a more complex shape to form, for example, curves,
angles, or discontinuous structures such as may be used to produce
impedance matching structures, phase control structures, diodes,
transistors, capacitive structures, inductive structures, resistive
structures, vias, or other structures, including those that can be more
complex or include combinations of such structures. As one example,
nanotube-based structures have been developed with integral bends that
have been shown to be capable of providing nonlinear electrical
responses. Such structures may act simultaneously as optical antenna
elements and nonlinear devices. Lithographic techniques can therefore be
used to repetitively produce a number of arrays of similar or dissimilar
components quickly and accurately.

[0100]In a typical photolithographic process, a protective photoresist
layer is deposited atop a substrate or other planar object that is formed
from a semiconductor material or metal. The photoresist layer is
patterned such as is generally known, with a variety of photo-based
development processes. An exposed portion of the material is then etched
or otherwise removed, for example, through ion beam or e-beam milling.
While this embodiment of a process is disclosed herein, a number of other
fabrication techniques may be appropriate. For example, direct e-beam
lithography, lift-off techniques, nanogrowth or other techniques may be
selected, depending upon the particular configuration, application,
dimensions, or other factors.

[0101]FIG. 4 shows an embodiment of an optical antenna assembly 100, in
which ring shaped optical antenna elements 102 are formed on the
substrate 202 using lithographic techniques, such that the materials may
be deposited according to known techniques. Deposition may be appropriate
in a variety of configurations, including those where the optical antenna
elements 102 can be on the order of some fraction of the wavelength of
the incoming or outgoing light.

[0102]While the optical antenna elements 102 of FIG. 4 are presented as
ring shaped, other geometric or non-geometric shapes may also be
selected.

[0103]In one embodiment, each optical antenna element 102 may be formed
with metals as gold, silver, aluminum, or copper. The antenna element
material may be provided, for example, by electrochemical deposition,
physical-vapor deposition, chemical vapor deposition, or may be grown in
a variety of manners. In certain embodiments, the optical antenna
elements may also be formed from semiconductor or similar materials such
as carbon or silicon based materials that can be typically doped or
otherwise combined with additional materials. In one embodiment, the
metal and/or semiconductor materials of the optical antenna element can
be selected to have a relatively high electron mobility. High electron
mobility materials have been developed to operate at relatively high
frequencies. For example, terahertz band high electron mobility devices
have been reported.

[0104]Minimum achievable dimensions of features produced by semiconductor
or similar fabrication techniques are steadily decreasing. The current
level of dimensions can produce many embodiments of the optical antenna
elements. For example, integrated circuit manufacturers have released
commercial devices with dimensions below 100 nm and have announced plans
for dimensions to a few tens of nanometers. It is expected that the
precision, dimensional control, manufacturability and other aspects of
the structures and methods described herein may benefit from such
technological developments. Such technological developments may be
expected to produce optical antenna elements having dimensions on the
order of a few tens of nanometers. In some cases, optical antenna
elements can have high vertical aspect ratios, for example 10:1 or
greater A dipole optical antenna element, or a non-regular antenna, of
700 nm, 350 nm, or 175 nm is therefore realizable using current
technologies.

[0105]Another technique that can be used to generate a number of
embodiments of optical antenna elements is e-beam lithography. Using
e-beam techniques, the user can precisely control the shape and
dimensions of a feature that is being produced. Many embodiments of
e-beam techniques provide for higher precision than current lithographic
techniques, and provide for forming features having dimensions down to a
couple of nanometers. As such, there can be a variety of techniques to
form an array of minute optical antenna assemblies. One relatively
straight-forward technique involves fabricating the optical antenna
elements as metal lines on a substantially uniform semiconductor silicon
substrate, or alternatively on a complex substrate such as a
silicon-on-insulator (SOI) substrate, a silicon-on-sapphire substrate, a
silicon-on-diamond substrate, or any other suitable configuration of
substrate (or other item that is configured to maintain the relative
position of the optical antenna elements) using conventional
semiconductor manufacturing approaches. Other materials, including
semiconductors, dielectrics,or conductors can form the substrate.

[0106]FIGS. 5a and 5b show one embodiment of the optical antenna assembly
100, including each of a plurality of nanotubes that form the array of
optical antenna elements 102 as carried by the substrate 202. Optical
antenna assemblies can include a large number and variety of
configurations of optical antenna elements, and can be formed as dipoles,
curved structures, discontinuous structures, etc. can be grown using
carbon-based nanostructure technology (e.g., using carbon-based or other
nanotubes). A large number of nanotubes can be grown to form an array of
optical antenna elements using nano-structure techniques by, for example,
having minute depressions initially being formed as a pattern upon a
substrate using such techniques as lithography. The locations of the one
or more depressions correspond to the desired locations of the nanotubes
to be grown. The patterned substrate is then located in a deposition
chamber for as long as desired depending upon the length of the
nanotubes. The locations of the patterned depressions can be referred to
in this disclosure as "seed regions" 504 since the nanotubes can be
selectively grown at the location of the patterned depressions.
Typically, nanotubes form as thin structures, ranging from one to tens of
molecules in diameter for different embodiments of the nanotubes. While
the exemplary embodiment herein is described as including ones to tens of
molecules, in some applications, nanotube diameters may exceed such
dimensions.

[0107]In the nanotubes, each optical antenna element 102 may be grown at
the location of a defect in a substrate. In certain embodiments, the
nanotubes can be grown at an angle with respect to the surface (including
parallel to the surface). Each optical antenna element can have
different, or even random, angular orientation with respect to the
surface of the substrate. In different embodiments, each nanotube can be
fabricated straight, or fabricated as having some curvature. In this
disclosure, the curvature can be considered as a non-regular antenna
configuration that is differentiated from the regular dipole antenna
configuration. The duration of growth and the rate of growth determine
the resulting desired height, angle, and curvature of each nanotube.

[0108]In certain embodiments, certain nanotubes can be even crossed or
crossed and joined to form an intersection point. As such, if a nanotube
of a particular height is desired to be formed, then the nanotube can be
allowed to grow for a prescribed time duration corresponding to that
length and rate of growth. Such approaches have been applied to produce
nonlinear devices such as transistors, diodes, and field emission
structures, as described for example in M. Ahlskog, R. Tarkiainen, L.
Roschier, and P. Hakonen, Single-electron transistor made of two crossing
multiwalled carbon nanotubes and its noise properties, Applied Physics
Letters Vol 77(24) pp. 4037-4039. Dec. 11, 2000; and Cumings and Zettl,
Field emission and current-voltage properties of boron nitride basedfield
nanotubes,

[0109]FIG. 5b shows a top view of one embodiment of the nanotubes as shown
in FIG. 5a. Multiple nanotubes that form an array can be grown to a
uniform height, or different heights, as desired. Many embodiments of the
nanotubes can be carbon-based, although any suitable material that can be
used and is within the intended scope of the present disclosure.

[0110]The array of the optical antenna elements 102 as described with
respect to FIGS. 5a and 5b can therefore be arranged in a
one-dimensional, two-dimensional, or three dimensional nano-structure
pattern, and may be either formed in a regular or an irregular pattern.
The embodiments of optical antenna elements 102 that are described with
respect to FIGS. 3, 4, and 5a may be used to fabricate either the
generating or receiving optical antenna elements 102 within the
respective generating or receiving optical antenna assembly 100. A number
of the different embodiments of the patterns of optical antenna elements
102 that form an array in the optical antenna assembly 100 are described
later in this disclosure.

[0111]A number of nanotube-based optical antenna element fabrication
techniques can use crystalline procedures, can use polymers, or even can
use biologically inspired polymers (such as deoxyribonucleic acid (DNA)
or proteins). The structure of the resulting nanotubes can be
crystalline. In certain embodiments, nanotubes can be conceptually formed
as a crystalline structure by forming a planar graph graphene sheet into
a cylinder, and capping the ends of the cylinder with a semi-spherical
"buckyball". Other configurations of, and processes for, forming
nanotubes or similar structures can also be within the intended scope of
the present disclosure. The crystalline approaches (including, but not
limited to, nanotubes and other nano-structures) might be more suitable
to optical antenna elements that can be arranged in a pattern
perpendicular to the plane formed by the waveform, either for a
generating or receiving optical antenna element. There can be, however,
also a number of different configurations of antenna design. Many optical
antenna assembly designs can leverage existing knowledge of optical
systems that operate, for example, in the microwave or millimeter range.
Depending on the particular embodiment, such optical antenna assemblies
could be applied to either broadband or narrowband antenna applications.

[0112]A number of different configurations of receiving optical antenna
assembly configurations can operate as detectors. One embodiment of the
optical antenna assembly simulates human vision by providing three arrays
of tuned optical antenna elements, with each one of the three arrays
being optimized or tuned for operation at the light frequencies that is
particularly detectable by human vision (red, green, and blue wavelengths
of light). Each of the three arrays of optical antenna elements can be
formed as a distinctive ring. For example, in one embodiment of an
optical antenna assembly, three arrays of optical antenna elements 102
form three concentric ring arrays (or other shapes of arrays) that can
each be configured/colored as red, green, and blue light-receiving rings
(not shown).

[0113]While the above describes an embodiment of the receiving optical
antenna assembly that detects a plurality of light frequencies
corresponding to colors such as red, green, and blue; it is also within
the intended scope of the present disclosure to provide multi-colored
generating optical antenna assemblies that generate or receive other
ranges of multi-colored light. Such multi-colored generating or receiving
optical antenna assemblies may be applicable to display and projector
applications, such as is likely for next generation television, display,
projector, computer, theater, or other similar applications. In other
frequency ranges, the multi-color or dual-color receiving or generating
optical antenna assemblies may be configured to operate in other visible
light ranges, or infrared or ultraviolet ranges.

[0114]Generating or receiving optical antenna assemblies may be configured
to generate/receive light of a variety of distinct frequencies, frequency
ranges, or combination of frequencies or frequency ranges, while
remaining within the scope of the present disclosure. For example, it may
be desired to use optical antenna elements that can generate or receive
light in the near infrared or near ultraviolet light spectrum, as may be
useful for a variety of applications, including thermal imaging,
ultraviolet illumination or detection, or any other appropriate
application. In other embodiments, it may be desired to generate/receive
light using a single frequency. Such transmission or detection may
provide more selectivity, simplified detection, synchronous operation,
and/or reduced cost or complexity. The particular light application
should be considered when determining the frequency of the generated or
received optical energy.

Examples of Optical Antenna Phase Techniques

[0115]FIG. 6 displays one embodiment of signals, which may be sinusoidal,
being generated by a plurality of optical antenna elements 102a and 102b
that together forms an associated signal-strength graph. FIG. 7 displays
one embodiment of FIG. 6 in which the highest amplitude generated light
is beamsteered upwardly by a few degrees with respect to FIG. 6. While an
array of optical antenna elements 102 would typically include a large
number of elements; only two optical antenna elements 102a and 102b are
illustrated in FIGS. 6 and 7 for clarity in describing certain
beamforming and beamsteering techniques. These concepts can be extended
to much larger arrays of optical antenna assemblies 100. Each optical
antenna element 102a and 102b radiates signal patterns such as are
illustrated in FIGS. 6 and 7 as respective signal lines 702a and 702b.

[0116]The respective signal lines 702a and 702b generated by the optical
antenna elements 102a and 102b are represented in the drawing as being
radiated in a generally hemispherical pattern. One skilled in the art
will recognize that the actual emission pattern from each of the
elements, including amplitude and phase, may depend upon the
configuration of the individual antenna element and on the materials
and/or structures of, surrounding, or near the individual elements. Thus,
patterns other than hemispherical may be within the scope of this
disclosure, though hemispherical is selected for clarity of presentation
of the concepts herein. Further, the description of propagation and
interaction of waves herein is simplified to a case where the waves are
typically of the same wavelength. This aspect lends itself in many cases
to coherent wave interaction. One skilled in the art will recognize that
variations in frequency, differences in frequency, non-coherent concepts,
and other types of interaction and related techniques and principles may
be applicable for certain configurations or applications of the methods
and structures described herein.

[0117]Also, only two-dimensions of the spherical pattern of the signal
lines 702a and 702b are shown in FIGS. 6 and 7 for clarity of
illustration, though typically, such configurations would be analyzed in
three dimensions using known techniques for analyzing beam propagation
and interference. Each signal line 702a and 702b represents, for example,
a crest of a sinusoidal pattern that is formed by respective optical
antenna elements 102a and 102b. The location where the signal lines 702a
and 702b intersect represents those phase intersection points 704 where
the signal lines 702a and 702b correspond to each other (are both at a
crest), and therefore can be in phase.

[0118]FIGS. 6 and 7 illustrate a number of phase intersection lines 706
that pass through many of the phase intersection points 704. The largest
and, typically, the strongest of the phase intersection lines 706a
corresponds to a main lobe 708 as shown in the signal strength plot.

[0119]The phase intersection lines 706a, 706b, and 706c determine the
locations where waves constructively add to form amplitude peaks. Two
additional phase intersection lines 706b and 706c correspond to side
lobes 710 in the signal strength plot in FIGS. 6 and 7. At any location
along the phase intersection lines 706a, 706b, and 706c, the signals from
both optical antenna elements 102a and 102b add constructively. As such,
the phase intersection lines 706a, 706b, and 706c typically correspond to
the highest light amplitude regions of the optical antenna assembly.

[0120]While FIGS. 6 and 7 present a simplified presentation of coherent
interaction, and demonstrate how formation of the main lobe 708, as well
as the side lobes 710, or the general direction of the phase intersection
lines 706a, 706b, and 706c follow antenna pattern techniques and
concepts, the availability of many elements and the control of element
positioning will often permit much more flexibility in relative position,
number, orientation, and other characteristics of the antenna assembly.
Designs utilizing such flexibility can be developed using conventional
analytical or computer based techniques for designing or analyzing arrays
of antenna elements.

[0121]Moreover, while FIGS. 6 and 7 illustrate either generating antenna
patterns according to the generating optical antenna elements 102a and
102b, such antenna pattern concepts can be also applicable to receiving
optical antenna elements. Antenna patterns, for both the generating and
receiving optical antenna elements 102a and 102b, correspond largely to
the relative phase and amplitude of the light-waves as indicated by the
respective signal lines 702a and 702b. For example, FIG. 7 shows that
changing the phases of the respective signal lines 702a and 702b can
change the location of the phase intersection lines 706a, 706b, and 706c
as well as the characteristics of the main lobe 708 and the side lobes
710 (characterized by the location, relative magnitude, width, or other
features). FIG. 7 illustrates the effect of shifting the phase of the
wave generated or received by the lower optical antenna elements by some
amount with respect to the waves generated/received by the upper optical
antenna element.

[0122]As such, the phase of the lower optical antenna element 102b is
altered (e.g. steered ahead) with respect to the phase of the upper
optical antenna element 102a by 180 degrees. This process of shifting the
phase of the signal that is generated by at least one of the optical
antenna elements 102 with respect to another of the optical antenna
elements to control directionality of the optical antenna assembly is
referred to herein as beamsteering for convenience, though the concept of
controlling the structure, direction and/or shape of the antenna pattern
may be addressed in contexts other than directing a beam of energy.

[0123]One skilled in the art will recognize that other actions relative to
controlling phase or relative phase may be directed toward other effects
as well, including possible lobe optimization, wave coupling, or other
effects. Moreover, the discussion herein has omitted the effects of
polarization or E-field orientation to simplify the presentation of the
concepts and principles. One skilled in the art will recognize that a
variety of analytical, experimental, and other techniques, as well as a
variety of structures may be applied to design, implement, analyze or
otherwise treat or understand polarization effects.

[0124]Beamsteering can also shift the relative positions of the main lobe
708 and the side lobes 710 with respect to the optical antenna elements
102a and 102b. Note, for example, that the main lobe 708 and the side
lobes 710 as described with respect to FIG. 7 are rotated in a generally
counter-clockwise direction when compared to FIG. 6. In a simplistic
example, increasing a gradient of the phase difference between waves from
different optical antenna elements increases shifting of the main lobes
and/or the side lobes. While the concept of beamsteering may become more
computationally involved as the number of the optical antenna elements in
an array is increased, conventional approaches can still be used.

[0125]This disclosure provides a number of embodiments of techniques by
which beamsteering, beamforming, antenna pattern control, or other
adaptive antenna techniques can be applied to optical antenna assemblies
100. Other embodiments of beamsteering and beamforming techniques across
a variety of arrays of optical antenna elements 102 may be within the
intended scope of the present disclosure.

[0126]As noted above, in some applications, the optical antenna elements
may be fabricated according to photolithographic or similar techniques
and may be on the order of a portion of an optical wavelength or a few
optical wavelengths. Consequently, in some configurations an optical
antenna assembly may include a large number, several thousand or even
millions of antenna elements 102. Moreover, in some configurations, a
1,000 by 1,000 element array may have a cross-sectional area on the order
of 1 mm by 1 mm. Such a small assembly may be useful as a component of a
variety of light capturing devices or systems, such as cameras, copiers,
scanner, optical detectors, or may be useful in many other light
capturing configurations. Additionally, components of such size may be
useful in light emissive applications ranging from illumination to
coherent beam generation.

[0127]While compact assemblies may have inter-element spacings on the
order of a portion of a wavelength to a few wavelengths, in some
applications it may be desirable to have larger inter-element spacings.
Such arrangements with increased spacing between the optical antenna
elements may be applied to such applications as synthetic aperture radar
(SAR) systems, sparse antenna arrays, radio telescopes, or the like.

[0128]Software that has been developed for, and supports the so-called
"synthetic aperture technique" and interferometric approaches. Such
software can be run, for example, in association with the optical antenna
controller 1700 as described below with respect to FIGS. 20, 17, 18, and
19.

Embodiments of Receiving and Modulating Approaches

[0129]In embodiments of optical antenna elements 102 that receive light as
described with respect to FIG. 1, it often is desired to detect or
otherwise process electrical energy generated within or around one or
more of optical antenna elements 102 responsive to the optical antenna
element. In many embodiments, it may be useful to process the electrical
energy at frequencies approaching the frequency of the incident light or
to process the electrical energy synchronously. While conventional
commercial electronic devices do not typically operate synchronously at
optical frequencies, the principles upon which such devices can be
designed and fabricated can be extensible to such frequencies, though
many effects, such as skin depth, that may be ignored at lower
frequencies may become significant at such higher frequencies. In fact,
such analyses are regularly presented and verified experimentally in the
literature relating to "plasmons" or "polaritons".

[0130]Within this disclosure, the signals (in both transmitting and
receiving embodiments of optical antenna assemblies) include any
propagation, including polaritons and phononic. As such, in this
disclosure, when reference is made to energy traveling or propagating
along an electrical path, it is intended that the propagation can include
within, adjacent to, outside of, parallel to, through, and any other
known conduction mechanism relative to an electrical path.

[0134]With polaritons, energy may considered to be propagated adjacent,
internal, and/or external to a guiding surface, such as a metal,
nanotube, photonic crystal, or other material.

[0135]In considering the optical antenna assembly, the relatively high
frequency of the light will impact the analysis and design. Light having
a wavelength of, e.g., 500 nm has a frequency of approximately 600 Thz,
while light having a wavelength of 30 microns has a frequency of about 10
THz and light having a wavelength of 300 microns has a frequency of about
1 THz. One skilled in the art will recognize that many commercially
available components typically used for lower frequency assemblies may
not yet be available at optical frequencies. However, as the scale of the
optical antenna elements is reduced to within one or a few orders of
magnitude relative to the wavelength of the optical waves, the
capacitance, inductance, and other parameters will also scale. As
operational frequencies of available components rise, the simplicity and
manufacturability of such devices is expected to improve. More details
regarding operation of certain embodiments of such components are
discussed below with reference to mixing.

[0136]Moreover, several techniques are becoming available for integrating
electronic or non-linear features into the optical antenna assembly. As
noted above, for example, carbon nanotubes having diode-like features
have been reported. Similarly, a number of nonlinear devices, such as
transistors, have been integrated in or analyzed in conjunction with
micro- or nanoscale structures such as nanotubes, and in some cases have
been described as operating at terahertz ranges. Example techniques and
descriptions can be found in the Ahlskog and Cumings references described
above as well as:

[0139]Antenna elements with integrated nonlinear devices can operate as
either or both of optical antenna elements 102 and mixers. In one
mixing-type of approach, the electrical energy may be mixed or otherwise
compared to a second electrical signal produced in response to a
reference optical signal. In some approaches, such as heterodyning, a
high frequency signal is mixed with a reference signal in a nonlinear
device, such as a diode or transistor to produce signals having a
frequency corresponding to a difference between the high frequency signal
and the reference signal. In one approach the reference signal is
generated with a local oscillator, according to techniques such as those
described for example in A. Maestrini, J. Ward, J. Gill; G.
Chattopadhyay, F. Maiwald, K. Ellis, H. Javadi, I. Mehdi; "A Planar-Diode
Frequency Tripler at 1.9 THz"; 2003 IEEE MTT-S Digest; January 2003; pp.
747-750; J. Ward, G. Chattoppadhyay, A. Maestrini, E. Schlecht; J. Gill,
H. Javadi, D. Pukala; F. Maiwald; I. Mehdi; "Tunable All-Solid-State
Local Oscillators to 1900 GHz"; Dec. 22, 2004, each of which is
incorporated herein by reference.

[0140]In some applications, information content of the optical signal may
be detected synchronously, through optical or electrical approaches. In
one optical approach, an optical reference signal is applied to one or
more antenna elements to produce a reference electrical signal.

[0141]The reference electrical signal and the electrical signal
corresponding to the received optical signal can be mixed, in a nonlinear
or similar signal processing device, such as a transistor, diode, or
bolometer to produce a downconverted signal component that may be
processed further. As noted previously, the nonlinear device may be
integral to or integrated with the optical antenna elements 102.

[0142]In some approaches, it may be adequate to process incoming optical
energy without specific phase information. In one such approach, the
antenna elements 102 convert incoming optical energy to electrical energy
and the electrical energy is integrated or accumulated over some time
duration. An example of a radiation detector that uses the bolometer
effect is described in the article: G. N. Gol'tsman, A. D. Semenov; Y. P.
Gousev; M. A. Zorin; I. G. Gogidze; E. M. Gershenzon; P. T. Lang; W. J.
Knott; K. F. Renk; "Sensitive picosecond NbN detector for radiation from
millimetre wavelengths to visible light"; Supercond. Sci. Technol.; 1991;
pp. 453-456; IOP Publishing Ltd, which is incorporated by reference as
well as in other references previously incorporated herein.

[0144]As noted previously, different embodiments of the signal processing
components that can be associated with each optical antenna element can
be configured as diodes, transistors, or other components as described in
this disclosure. In the FIG. 8 embodiment, the optical detector 804 is
configured as a diode 808. There can be variety of embodiments of diodes
808 that can be used. In FIG. 8, the diode 808 is represented
conventionally with a p-region 810 that is positioned adjacent to an
n-region 812, though a variety of structures may be applicable. Such
p-regions 810 and n-regions 812 are typically formed by doping according
to known techniques. One skilled in the art will recognize that other
diode or other nonlinear structures may be appropriate for certain
applications. For example, planar diode multipliers, Schottky diodes,
field emission devices, and HEMT devices are described hereinbelow and in
various references incorporated herein. In many cases the particular
component may be designed specifically to interact with its respective
one or more optical antenna elements 102.

[0145]For example, in many embodiments, the magnitude of the electrical
signal produced by the one or more of the optical antenna elements 102
corresponds to the amplitude of the optical wave interacting with it. In
some applications, the electrical signal will propagate in a manner
corresponding to its frequency and the structure of the optical antenna
elements 102 and the electrical conductor. For example, where the
electrical signal is at very high frequencies, it is likely to be carried
in the form of a plasmon. The plasmon is guided by the electrical
conductor or by the optical antenna element to, or near, the nonlinear
component, where the plasmon may produce a change in an electric field
in, around, adjacent to or otherwise interacting with the component. The
component responds to the interaction by producing a corresponding output
electrical signal. A variety of interacting approaches may be applicable.

[0146]The optical antenna elements and their associated signal processing
components, as described with respect to FIGS. 8 and 9, may include a
nonlinear device such as a diode or transistor integrated with or coupled
to optical antenna elements. As shown in a diagrammatic representation in
FIG. 8, the n-region 812 of diode 808 carries an optical antenna element
102. The n-region 812 is integrated into a substrate 202 that includes a
p-region 810. As is known adjoining n and p-regions can form a diode,
thus forming a nonlinear device. As is also known, nonlinear devices,
such as diodes can form portions of rectification or signal processing
circuitry. While the diagrammatic representation of FIG. 8 shows the
diode being physically discrete from and carrying the optical antenna
element 102, the diode may be incorporated into the diode as is noted
hereinbelow. Moreover, although the representational diode 808 of FIG. 8
includes a pn-junction, other configurations, such as those including
Schottky diodes may be more appropriate in some configurations. Such
diodes and integration with waveguides, nanotubes, and other components
are referred to hereinbelow and in several of the references incorporated
herein by reference.

[0147]In a transistor type of implementation presented in FIG. 9, an
optical detector 804 that responds to the electrical signal induced in
the optical antenna element 102 includes a transistor 908. The embodiment
of transistor 908 that is described with respect to FIG. 9 is a
field-effect transistor (FET), as indicated by the identity of the
terminals (a source 910, a gate 912, and a drain 914), though other
transistor configurations may be appropriate in some configurations, as
noted below.

[0150]Returning to the description of exemplary transistor 908, upon
arrival of an optical wave at the optical antenna element, the induced
electrical signal in the optical antenna element 102 produces a change in
a field in the gate 912 of the transistor that produces a corresponding
amplified output according to principles of transistor operation. The
transistor may be configured for additional gain, selectivity, or
interaction with the electronic circuitry. For example, the channel width
and other parameters may be configured to be resonant at a frequency
corresponding to the frequency of an input wave. An example of
transistors configured for resonant operation is described in V. Ryzhii,
I. Khmyrova, M. Shur; "Terahertz photomixing in quantum well structures
using resonant excitation of plasma oscillations"; Journal of Applied
Physics; Feb. 15, 2002; pp. 1875-1881; Volume 91, Number 4; American
Institute of Physics and in W. Knap, Y. Deng, S. Rumyantsev, M. S. Shur;
"Resonant detection of subterahertz and terahertz radiation by plasma
waves in submicron field-effect transistors"; Applied Physics Letters;
Dec. 9, 2002; pp. 4637-4639; Volume 81, Number 24; American Institute of
Physics.

[0151]It is noted that the components of the traditional diode (see FIG.
8) or a Schottky diode 1003 (FIG. 10), or the transistor that is
associated with the optical antenna element 102 (see FIG. 9) can either
be formed either on, or in, the substrate 202 as shown in FIGS. 3, 4, 5a,
and 5b. As device speeds increase due to improvements in technology, the
particular device that is selected to be associated with the optical
antenna assembly may vary depending upon the application, configuration,
frequency, fabrication considerations, or other considerations. As such,
in this disclosure, the particular processing or mixing devices described
herein are illustrative in nature, and not limiting in scope.

[0152]Moreover, many embodiments of the optical antenna elements 102 as
described relative to FIGS. 8 and 1 through 5b can be formed partially or
entirely with metal, semiconductors, carbon, or other materials that may
be compatible with fabrication processes for many types of electronic
components. Consequently, portions of the optical antenna elements 102
can correspond to or be integral with the portions of one or more
Schottky diodes, transistors, or other components. For example, where an
optical antenna element 102 is metal, it may be integral with or actually
form an electrode of the Schottky diode 1003 as shown in FIG. 10.

[0153]In a number of embodiments, signal processing techniques may be used
to process and/or transfer information derived from one optical antenna
assembly to another location. One signal processing technique that is
particularly applicable is conversion between the time domain and the
frequency domain. For example, the detected intensity values for a
receiving optical antenna assembly can be sampled, and the quantized
sampled values converted, such as with a Fourier Transform or
Fast-Fourier Transform filter to obtain frequency domain information that
is representative of the light received at all of the optical antenna
elements across the receiving optical antenna assembly. This frequency
domain information can be processed, stored, or transferred to a
different location depending upon the desired use of the receiving
optical antenna assembly.

[0154]An inverse operation can generate a desired light signal or image
with the transmitting optical antenna assembly applies frequency domain
information to such a device, such that the device selectively emits the
equivalent of a spatial Fourier transform of an intended image. As is
known, a conventional lens can act as a spatial Fourier transforming
device and thus can convert the waves emitted by the optical antenna
assembly to a "real world" image represented by the information applied
to the optical antenna assembly.

[0155]In one embodiment, the optical antenna controller 1700 as described
with respect to FIG. 19 may generate the spatial frequency domain
information to be applied to the optical antenna assembly, from
conversion of a real world image, from an analytical source, such as
optical design, modeling, or analysis software, or from information
supplied from another source.

[0157]FIG. 11 shows one generalized representation of a feedback system
that may operate as an oscillator 1102. Such basic diagrammatic
structures are commonly described in a variety of technologies, such as
those relating to control systems, antenna systems, microwave systems,
and analog circuits. Generally speaking an input signal arrives at the
summer Σ where it is combined with a feedback signal from a
feedback element f1 to produce an combined signal that drives a gain
element G. The gain element G amplifies the combined signal to produce an
output signal VOUT.

[0158]Where the loop gain is greater than unity, the system output signal
will grow until some other system parameter limits the overall loop gain.
Where the system is intended as an oscillator, the feedback element
f1 may be a frequency filter so that the overall system oscillations
are sinusoidal at a selected frequency.

[0159]While one basic form of the oscillator 1102 is presented
diagrammatically in FIG. 11, one skilled in the art will recognize that
the actual oscillator configuration will depend upon the particular
application, including frequency of operation, type of gain element,
desired or available quality factor Q of various components and filters,
and other operational and design considerations. For example, the
frequency may be determined in part or in whole by a frequency selective
component of the gain element G. Thus, references to the feedback element
f1 herein may be applicable to the forward gain portion of the
system, in lieu of, or in addition to the feedback portion of the system.

[0160]Moreover, systems involving more than one feedback loop, systems
having a separate driving source for gain, and systems having the gain
and feedback portions integral to a single component may be appropriate
for certain applications. Additionally, oscillators or signal sources may
be presented in a variety of other diagrammatic or conceptual
representational approaches.

[0161]In a general case, the oscillator output signal VOUT can drive
one or more antenna elements described elsewhere herein. Where the output
signal VOUT is at optical frequencies, it may provide a carrier
signal, driving signal, or reference signal directly, or may be frequency
converted to produce a carrier signal, reference signal, or driving
signal for the optical antenna element.

[0162]While the feedback element fi is represented as a basic diagrammatic
block in FIG. 11, FIG. 12 shows, representationally, one type of
structure 1202 that can, in part, define the system frequency of
oscillation and Q. In this system, a molecule or other structure, such as
a quantum dot, which may be a separate element or may be incorporated
into a larger structure, such as a crystal lattice, receives input
energy. The received energy may come in part from the system output,
Vout as shown in FIG. 12. The structure 1202 resonates at a
frequency defined, in part, by its physical and electromagnetic
characteristics, such as available quantum states of electrons or mass of
molecules. One skilled in the art will recognize that FIG. 12 is merely
representational of molecular structures where a nucleus N is surrounded
by electrons e-. The energy levels, bond strengths, and other aspects of
the molecular structure define resonances at which the molecule will
naturally respond, and FIG. 12 is presented representationally for
clarity of presentation. Moreover, oscillators need not rely on natural
frequencies of molecules in many applications. For example, oscillators
employing molecular or quantum dot based resonators have been produced at
a variety of frequencies. For example, lasing based upon quantum dot
oscillations is described in "Lasing from InGaAs/GaAs quantum dots with
extended wavelength and well-defined harmonic-oscillator energy levels,"
G. Park, O. B. Shchekin, D. L. Huffaker, and D. G. Deppe, Applied Physics
Letters Vol 73(23) pp. 3351-3353. Dec. 7, 1998.

[0163]In some implementations, the feedback element f1 may include a
plurality of separate or integral structures, components, or elements
that provide feedback and/or frequency selectivity. As noted previously,
such structures may be in the feedback portion of the system, in the
forward gain portion of the system, or in both.

[0164]While the description of FIG. 11 presents the oscillator, other
sources of a carrier signal, reference signal, or driving signal may be
appropriate in many cases. For example, one embodiment of a system that
mixes the reference signal with a received signal employs a separately
generated reference signal at the optical frequency. In one approach, a
laser, such as a microlaser, laser diode, dye laser, or other type of
known laser produces the reference signal.

[0165]In such systems, the output signal is typically an optical beam, at
a frequency on the order of tens to hundreds of terahertz. The type of
lasers selected may depend upon the desired wavelength, power, cost,
portability or other aspects.

[0166]In one configuration, the signal from the reference source is
directed toward one or more of the optical antenna elements 102. As
described previously, the optical antenna elements convert energy in the
incident reference beam into a reference electrical signal carried by a
portion of the optical antenna element 102.

[0167]The signal from the reference source may be applied to the same
optical element that is operating as a receiving optical antenna element
to produce a response in the optical antenna element 102 that is a
composite of the response corresponding to the received optical signal
and the response corresponding to the reference optical signal. An
example of a reference optical signal mixed with a second signal to drive
a dipole antenna is described in the article I. C. Mayorga, M. Mikulics;
M. Marso; P. Kordos; A. Malcoci; A. Stoer; D. Jaeger; R. Gusten; "THz
Photonic Local Oscillators"; September 2003; Max-Planck-Institute for
Radioastronomy, which is incorporated herein by reference, and as
obtained from the site:
http://damir.iem.csic.es/workshop/files/03092003--17h50_Camara.pdf.

[0168]Alternatively, as shown in FIG. 13, the signal from a reference
source 1302 may be applied to optical antenna elements 102A different
from the optical antenna elements 102 operating as receiving optical
antenna elements. The electrical signal corresponding to the received
optical signal, and the electrical signal corresponding to the reference
optical signal, can then both be coupled to an electrical conductor 1304,
such as a waveguide, component, or polariton propagating material, that
produces an output that is a composite of the electrical signal. Such an
approach may be applicable in a variety of other physical configurations,
and may be complementary to the approaches described below with reference
to FIGS. 15 and 16.

[0169]In another alternative approach, a reference signal may be formed
according to optical irradiation of semiconductor or nonlinear optical
materials that, in turn, produce polariton propagation as can be found in
N. Stoyanov, D. Ward, T. Feurer, K. Nelson; "Terahertz polariton
propagation in patterned materials"; Nature Materials-Letters; October
2002; pp. 95-98; Volume 1; Nature Publishing Group, which is incorporated
herein by reference. In such an approach, generated polaritons arriving
at an optical antenna element or at an electronic component provide a
phase reference for electrical signals produced by the optical antenna
element.

Examples of Phase Comparators

[0170]FIG. 14 shows diagrammatically one embodiment of a phase comparator
1400 that includes a combined optical antenna element array 1402 and a
reference waveform generator 1404 that produces a reference waveform
1407, presented as traveling left to right in FIG. 14. One skilled in the
art will recognize that the diagrammatically represented components may
form a portion of an optical antenna assembly, as described hereinabove.
Each optical antenna element 102 in the array may generate and/or receive
any given phase with respect to the other optical antenna element in any
desired spatial location. Control of the relative phases between the
optical antenna elements can allow beamforming, gain control, or other
features, as described previously.

[0171]In a receiving configuration, as illustrated in FIG. 14, the
combined optical antenna element array 1402 includes a number of
receiving optical antenna elements 102 and corresponding comparators
CX (where X=1, 2, 3, . . . , n). Each comparator CX also
receives the reference waveform 1407 at a respective relative phase. In
the receiving configuration, the comparator CX compares the phase of
the signal received by the optical antenna element 102 relative to the
reference waveform 1407 to determine the relative phase of the receive
signals at each optical antenna element 102.

[0172]Where the direction of field of interest is to be controlled, the
comparators CX may include respective phase adjusters
ΔφX, that shift the phases of the corresponding signals
received by their respective optical antenna elements. One skilled in the
art will recognize that the same basic structure may be applied to a
transmitting or generating embodiment, where combiners would be
incorporated instead of the comparators. Moreover, the representation of
FIG. 14 is diagrammatic and some of the aspects presented separately or
as integral in FIG. 14 may be realized in one or more components in some
configurations. For example, the phase comparator may be integral to the
optical antenna elements or combiners in some configurations and the
phase adjusters may be integrated into a single component or a few
components that may be separate from the combiners. Moreover, the
comparators or phase adjusters may be active or passive structures.

[0173]Additionally, the relative positions and/or orientations of the
devices or components may be changed or even reversed depending upon the
selected system architecture. For example, the phase adjusters may be
positioned to control the phase of the reference signal in a receiving
configuration or may be positioned to adjust the phase of the generated
signals after the signals can be emitted by their respective optical
antenna elements.

[0174]With the embodiment of the reference planar waveform generator 1404
as described with respect to FIG. 14, the reference waveform arrives from
a direction substantially parallel to a plane containing the array of the
optical antenna elements (e.g., from left to right in FIG. 14) such that
each of the optical antenna elements receives the reference planar
waveform at a respective relative time. In such configurations where the
reference waveform travels in, or at an angle non-orthogonal to, a plane
containing or parallel to the optical antenna elements as represented in
FIG. 14, the relative time difference will be, at least in part, a
function of the inter-element spacing and the propagation velocity of the
reference waveform.

[0175]In the configuration of FIG. 15, the reference wave arrives at all
of the optical antenna elements or combiners 1502 substantially
simultaneously. Here, the reference waveform is presented as traveling
parallel to the central direction of the generated or received waveform,
though other orientations may be selected depending upon design
considerations. The applied reference waveform therefore moves in a
generally upward direction as illustrated with respect to FIG. 15. In
this representation, the reference waveform thus arrives orthogonally
relative to the plane containing the optical antenna elements. Angles
other than parallel or orthogonal to the plane containing the optical
antenna elements may also be selected. One approach to providing the
reference waveform was described above with reference to FIG. 13,
although the reference waveform may be a signal carried along a
conductor, such as a wave of polaritons having defined relative phases.
Such waves have been presented and imaged in the literature, e.g., David
W. Ward, Eric Statz, Jaime D. Beers, Nikolay Stoyanov, Thomas Feurer,
Ryan M. Roth, Richard M. Osgood, and Keith A. Nelson, "Phonon-Polariton
Propagation, Guidance, and Control in Bulk and Patterned Thin Film
Ferroelectric Crystals," in Ferroelectric Thin Films XII: MRS Symposium
Proceedings, Vol. 797, edited by A. Kingon, S. Hoffmann-Eifert, I. P.
Koutsaroff, H. Funakubo, and V. Joshi (Materials Research Society,
Pittsburgh, Pa., 2003), pp. W5.9.1-6.

[0176]Also, although the reference above has been to a plane containing
the optical antenna elements, other non-planar structures, including
curved, layered, or other configurations may be selected. In each of
these configurations, one or more reference signals may be supplied to
the optical antenna elements. Further, although FIG. 14 presents the
reference signal as arriving from a direction perpendicular to a plane
containing the optical antenna elements and FIG. 15 shows the reference
signal as arriving from "behind" the optical antenna elements, in some
approaches the reference signal may arrive from the "front" of the
optical antenna elements. That is, the reference signal and the generated
or received signal may arrive or depart from the same general side of the
optical antenna assembly. Moreover, other embodiments may employ more
than one reference signal and may employ combinations of reference
signals.

[0177]Additionally, the reference waveform need not be a planar waveform,
or even a substantially planar waveform. For example, non-planar
waveforms may be desirable in some applications. One relatively
straightforward approach to producing a non-planar reference waveform is
to insert a non-uniform phase delay structure, such as a non-uniform
phase plate or an active array of phase delay structures between the
reference waveform generator 1404. Where the optical antenna element
array 1402 is configured as an optical receiver, signals from the
reference planar waveform generator 1404 received at different times (and
as such, signals received in different phases) among the different
optical antenna elements, may be monitored and adjusted, or otherwise
considered. As an example, assume that the phase of a signal generated or
received at a first optical antenna element 102 relative to the reference
signal differs from the phase of a signal a second optical antenna
element 102.

[0178]Where the reference waveform is formed from polaritons, the
reference waveform may be a composite formed from a set of polariton
generators, such as a set of emissive structures or a set of apertures in
a material.

[0179]In one embodiment, the phase adjusters ΔφR can be
controlled by an electronic controller to include, e.g., a
general-purpose computer, a microcontroller, a microprocessor, an
application-specific integrated circuit, or any other type of
computer-based, logic-based, mechanical controller, electromechanical
controller, or other type of a controller. The controller can optionally
have input from the user to control the beamforming, beam steering, or
other operations. Phase adjusting of signals may be accomplished
according to a variety of known techniques that may be adapted to the
frequencies herein. In a straightforward case, a fixed phase mask may be
defined to provide a passive form of phase control. One such approach to
phase control is described in "Coherent optical control over collective
vibrations traveling at light-like speeds," R. M. Koehl and K. A. Nelson,
J. Chem. Phys. 114, 1443-1446 (2001); "Spatiotemporal coherent control of
lattice vibrational waves," T. Feurer, J. C. Vaughan, and K. A. Nelson,
Science, 299 374-377 (2003); and "Typesetting of terahertz waveforms," T.
Feurer, J. C. Vaughan, T. Hornung, and K. A. Nelson, Opt. Lett. 29,
1802-1804 (2004), each of which is incorporated herein by reference.

[0180]In such a circumstance, the phase adjusters ΔφR of at
least one of the two optical antenna elements 102 can be adjusted to
reduce, eliminate, or otherwise control the in relative phases. The
amount, direction, and other aspect of the relative phases can be
determined according to the desired response of the antenna assembly 100.
For example, pairs of elements may be excited and the relative minima and
maxima of their farfield patterns may be determined. Alternatively, the
general gain of the optical antenna elements along paths may be monitored
and the relative phases of one, two, or more of the optical antenna
elements adjusted according to an intelligent searching approach to
establish the beam pattern according to a determined set of criteria
(e.g., side lobe levels, central lobe gain, or similar criteria.).

[0181]FIG. 16 shows another embodiment of phase comparator 1600 that
compares, and adjusts, the phase of a reference signal that is generated
by multiple receiving optical antenna elements (instead of a reference
signal being received as in the embodiment of FIGS. 14 and 15). The
relative phases of the relative optical antenna elements 102 can be
adjusted by adjusting the respective phase adjusters ΔφT.
The phase comparator 1600 of FIG. 16 differs from the phase comparator
1400 of FIG. 14 in that the reference planar waveform generator 1604 is
configured to apply a reference wave that is perpendicular to the
orientation of the optical antenna elements of the combined generating
visible frequency element array 1602. As such, the reference waves can be
received at each of the multiple receiving optical antenna elements 102
at a different time corresponding to the time necessary for the reference
wave to travel to each respective optical antenna element from a
preceding optical antenna element.

Examples of Regular Configurations of Optical Antenna Elements

[0182]Optical antenna elements may be fabricated according to a variety of
techniques including, but are not limited to, photolithography,
lithography, nano structure growth, and attaching separately grown nano
structures a substrate or other support. Optical antenna elements may be
classified as either regular or non-regular. As described above, with an
this disclosure, the term "uniform", pertains to regular or statistically
regular arrays of optical antenna elements that extend substantially
continuously across a portion of, or an entirety of, an optical antenna
assembly.

[0183]Conceptually, perhaps one easy configuration of optical antenna
elements to consider are those in which each optical antenna elements are
uniformly spaced from the neighboring optical antenna element, and each
optical antenna element extends substantially perpendicular to the
substrate or other supporting member. As the dimensions of each optical
antenna element are typically minute spacing of the optical antenna
elements may not be exactly regular. Additionally, it might be difficult
in many embodiments to ensure that the optical antenna elements extend
substantially perpendicular to the substrate or supporting member. As
such, the term "regular" pertains in many embodiments to the location of
attachment of the optical antenna elements across the substrate. For
example, growing optical antenna elements from a number of regularly
spaced seed locations can produce a substantially regular array of
optical antenna elements within an optical antenna assembly, even though
many of the optical antenna elements may extend at angles other than
orthogonal with respect to the substrate, as represented in FIG. 22. For
a large number of the optical antenna elements and a limited range or
appropriate distribution of angles at which the optical antenna elements
extend from the supporting structure, the overall resulting operating
characteristics of many embodiments of the optical antenna assembly may
have substantially repeatable, predictable and/or determinable
electromagnetic characteristics.

[0184]A large number of other fabrication techniques can be used to
produce regular arrays of optical antenna elements. For example,
lithographic patterning techniques, e-beam lithography, and nano
structure epitaxial growth can be utilized. Grown nanostructures can be
separated, and reattached to the supporting member to produce a
statistically regular configuration of the optical antenna elements.

[0185]Another embodiment of regular optical antenna assembly is
represented in FIG. 23, in which a number of patterned rectangles 2304
are formed in a substantially horizontal configuration across the
substrate or supporting member. The patterned rectangles 2304 may be
formed in one embodiment using lithography, photolithography, or some
other etching, growth or other fabrication technique.

[0186]The spacing and dimensions of the patterned rectangles is selected
to correspond to the intended operational frequency of the optical
antenna elements. Typical photoconductor or processing techniques can be
used to produce the structures, as are generally known by those skilled
in the art of semiconductor processing.

[0187]Although the embodiment of FIG. 23 includes rectangular optical
antenna elements 2304, a variety of other structures, including those
having hexagonal, circular, elliptical, or other cross-sections may be
appropriate for some configurations. Moreover, although the optical
antenna elements 2304 are represented as structures that extend from a
base, other structures, such as recesses, apertures, or voids or
structures that extend laterally or in other directions may be suitable.

Examples of Applications in Systems

[0188]This disclosure now provides a number of different embodiments of a
plurality of optical antenna elements 102 that can be configured in an
array. A number of embodiments of optical antenna assemblies may be
operable to produce waves appropriate for interferometric applications.

[0189]Interferometric applications, including interferometer-based optical
imaging or measurement, include telescopes, including those that have
allowed astronomers to measure the diameter of stars, distance measuring,
photolithographic applications, surface topology, speed measurement,
surface topology measurements, distance measurements, and a variety of
other applications. The configurations of such interferometers can apply
similar principles to those described with respect to FIGS. 6 and 7.

[0190]In addition to general measurement applications, coherent techniques
can be configured to provide a variety of embodiments of a holographic
projector, as described below, including holographic devices for image
presentation. One embodiment of optical interferometers described with
respect to this disclosure includes solid state interferometers. Such
solid-state optical-domain interferometers operate by mixing the received
light, and extracting phase information from the mixed signal without
leaving the optical domain. One aspect of certain embodiments of the
optical interferometers can be characterized as operating as "digital
interferometers." In one approach a digital optical interferometers
includes a digital computation device that selectively controls the
amplitude and/or phase of a number of the optical antenna elements. The
selected relative phase and/or amplitude may be determined analytically,
through calculations or other approaches, may be determined empirically,
or may be retrieved from memory. In one embodiment, solid state
optical-domain interferometers can be microelectromechanical system
(MEMS) based. In another embodiment, such solid state optical-domain
interferometers can be configured to operate relying upon non-MEMS
optical switching techniques.

[0191]A variety of approaches to preparing or producing data to store in
memory or to provide to the computation device may be appropriate. In one
application, the data is generated by capturing an image, including phase
information with an optical antenna assembly-based device or other type
of holographic device.

[0192]A variety of numerical techniques, such as those known for
conventional phased arrays and holographic techniques, may be applied to
produce the digital data for captured, displayed, or projected images. In
one approach where each optical antenna element produces a signal
indicative of an arriving wave, the input is sampled, typically at a
frequency approaching, substantially equaling, or exceeding the frequency
of the received light, and the sampled data is processed digitally.
Computer techniques and hardware continue to increase processing speeds
to further improve the accuracy and performance of the digital imaging.

[0193]In some applications, the data or information may be captured at a
first location, or set of locations, and then propagated to a second
location where an image is presented, as a display or holographically
presented image. Moreover, the data or information to be generated may be
compressed or replaced or supplemented by representative data to increase
the speed or reduce system burden for information transmission.

[0194]The number, arrangement, location, material, and other properties of
the optical antenna elements may vary greatly depending upon the
particular design considerations. However, as an exemplary embodiment of
an application that may utilize coherent imaging or interferometric
approaches, a receiving optical antenna assembly may operate similarly to
a miniaturized so-called Keck telescope or a very large array (VLA) radio
telescope employing waves at optical frequencies.

[0195]Certain techniques described herein, relating to interferometers,
can also be applied to design and construct cameras that can be
configured as detectors, as described above. The basic interferometer
approach could therefore be applied to detectors formed from a regular or
non-regular array of optical antenna elements or sets of arrays of
optical antenna elements. Depending upon various design considerations,
the dimensions of the array may range from postage stamp size to
billboard size, and even outside of these dimensions. At some physical
optical antenna element dimension, the optical antenna elements of the
optical antenna assembly can be fabricated to be self-supporting, and it
may be appropriate to fabricate the substrate separately from the optical
antenna elements. In other embodiments, the optical antenna elements can
be supported separately from a substrate or set of substrates.

[0196]One embodiment of the receiving optical antenna assembly can be
configured to form one embodiment of an extremely "thin" imager. In such
an approach, the operational circuitry can be disposed in a separate
structure or may have integrated operational circuitry. In one
application, the imager may be configured as a portion of a camera that
may allow the camera to have features different from conventional
cameras. In one approach, additional portions of the optical antenna
assembly, such as a phase control assembly can provide directionality or
gain that can supplement or replace some portion of the conventional
focusing optics in a camera. In some applications, the imager
functionality may be sufficient to completely replace the conventional
optics. In other applications, the imager functionality may incorporate a
combination of conventional optics and an array of optical antenna
elements.

[0197]Where the optical antenna assembly is used without separate discrete
optics or is configured with microoptics, the optical antenna-based
camera can be configured with a thickness corresponding to the thickness
of a semiconductor-based chip integrated into the camera (e.g., having
dimension on the order of one or a few mm), and depending upon the
application may have an acceptable effective aperture size, focal length
or other properties.

[0198]In one embodiment, as described above, digital sampling provides an
effective Fourier Transform by controlling/activating selected elements
or phase controls. This may allow for a self-correlating optical imaging
device. While above descriptions include periodically spaced arrays of
elements, other configurations may be selected. In one embodiment, one or
more optical antenna elements 102 form an annular ring on a substrate 202
as presented diagrammatically below with respect to FIG. 17.

[0199]This configuration including phasel taps 1702 provides a discrete
set of phase directions that can adjust the relative phase. This can be
viewed as a phase scanning version of pixels. The set of taps in effect
defines the "phasels" that mix light from various parts of the ring of
optical antenna elements. The number and spacing of the phasels determine
the angular resolution, in part.

[0200]One such embodiment of electrical domain interferometer can be
implemented using certain digital approaches. For example in one aspect,
phasel taps can be configured as the φ-adjusts that rely upon delay
lines whose delay time can be individually modified. Another approach to
phase control involves physically modifying the relative positions or
dimensions of the optical antenna elements 102.

[0201]Yet another aspect of the φ-adjusts 104 includes approaches that
control relative signal delays with something other than physical length
(e.g., altering material properties, constructing waveguides with reduced
propagation velocities, etc.). An example of such analysis in the
microwave range that would be substantially directly applicable to the
optical antenna assembly is described in Chiang, et al., Microwave Phase
Conjugation Using Antenna Arrays, IEEE Transactions on Microwave Theory
and Techniques, Vol. 46, No. 11 (November 1998), which gives examples of
analyses of 8-element and 40-element microwave antenna arrays, and which
is incorporated herein by reference. While such design or control may be
performed analytically, empirical or statistical approaches may also be
applicable. For example, statistical approaches to beam forming or
directional determination may be applied to the optical antenna assembly.

[0202]Another embodiment of an optical antenna assembly-based device
employs scanning techniques. In one embodiment, an image is displayed or
captured by scanning and controlling a pixel by pixel basis. Scanning may
be by a physical device, such as a MEMS, acoustooptic, or similar
scanner, may be implemented by controlling phase and amplitude of the
signals at each respective optical antenna element, or may be a
combination of both.

[0203]Many signal switching or modulation techniques can provide
selectivity of signals from respective ones or groups of optical antenna
elements. For example, one exemplary approach applies interference of
signals, with a structure such as a Mach-Zender interferometer to
selectively transmit some or all of the signal from respective optical
antenna elements to the respective desired locations.

[0204]In a simplistic example of interference according to the structure
of FIG. 13, energy is traveling, for example, from the left optical
antenna element 102A (left to right) mixes with a signal from the right
optical antenna element 102. If the signals have the same amplitude and
are a half wavelength out of phase at a given location, to a first order,
the net signal at the location will be substantially zero. The amplitude
will vary depending upon the amplitude of the received signal relative to
the amplitude of the reference signal, and/or the relative phases of the
signals.

[0205]Rather than attempting to detect in all directions from a set
optical antenna elements positioned within one plane, it may be desired
in some embodiments of the optical antenna assembly, to use a plurality
of antenna assemblies, each having a respective field of regard. Each of
the antenna assemblies may have a fixed field of regard, or may be
scannable. Moreover, the respective fields of regard may be
non-overlapping or partially overlapping.

[0206]Where the fields of regard are separate, it may be advantageous to
vary the relative phases within a smaller range as compared to the phase
ranges corresponding to addressing a larger field of regard. Directing
respective optical antenna assemblies at respective orientations can
allow an overall system to monitor a wide range of fields of view or to
emit light over a relatively wide range. In some cases, the size of the
arrays of optical antenna elements may allow a plurality of arrays to be
assembled in a single unit or a few units. This may enable a compact
system with a relatively large field of view.

[0207]Consider a 2D array of the phasel taps that can be configured, in
the embodiment as described with respect to FIGS. 1 and 2, as the
φ-adjust 104. The combiner 106, as described with respect to FIG. 1,
is configured to mix the input from any group of optical antenna elements
having the desired combination of phase delays between a minimum value
and a maximum value.

[0208]One relatively simple approach to increasing the response speed of
the phasel taps (e.g., the φ-adjust 104) includes providing each of
the phasel taps with a set of discrete phase delays, each corresponding
to respective a substantially fixed angular increment or relative phases.
The relative phases between respective optical antenna elements 102 can
be adjusted by selectively coupling one or more of the discrete phase
delays.

[0209]After signals from a plurality of the receiving optical antenna
elements 102 are down-converted (e.g., by mixing), the output
down-converted signal is then processed with appropriate electronic
circuitry. In one approach, the electronic circuitry includes an
analog-to-digital (A/D) converter that produces a digital signal
representative of the down-converted signal. While the described
implementation employs electronic circuitry including the A/D converter,
a variety of other approaches to processing or otherwise handling
downconverted signals may be appropriate, including analog filtering,
sampling, or other known approaches.

Examples of Configurations of Regular and Non-Regular Arrays of Optical
Antenna Elements

[0210]In many embodiments of the optical antenna assembly, an array of
optical antenna elements may be arranged in a pattern other than an
N×N matrix where each location includes one or more antenna
elements. One example described previously is the ring arrangement of
FIG. 17.

[0211]In another arrangement, a set of antenna elements may be arranged
according to an N×N matrix of positions, with one or more of the
positions in the matrix being empty. In some cases, a substantial
portion, which may be more than half of the positions, may be empty. The
positioning, response, design and other features of such a design may be
determined according to techniques for sparse-array antenna structures.
Examples of such analyses may be found, for example, in Athley
Optimization of Element Position for Direction Finding with Sparse
Arrays, self-identified as published at IEEE Proceedings of the 11th
Workshop on Statistical Signal Processing, Aug. 6-8 2001 (Singapore).

[0212]A less than full (two-dimensional) array of optical antenna elements
may simplify fabrication and computation in some applications, while
providing substantially the same information as a full array of optical
antenna elements. A more sparsely populated array may address
substantially the same field of view and acquire substantially the same
information by sequentially addressing a set of fields of view. In one
approach such an array includes a set of associated φ-adjusts 104
configured as phasel taps, or individually-controllable delay lines, as
described with respect to FIGS. 1 and 2. The output from the different
relatively few sets of the optical antenna elements can be combined to
produce a set of information that approximates that of a more densely
populated array.

[0213]A number of embodiments of the optical antenna assembly may include
arrays of optical antenna elements that have periodic or aperiodic
spacing of the optical antenna elements. Selection of periodic or
aperiodic spacing, the inter-element spacings, or the selection of
patterns may depend in part upon the shape, sidelobes, gain, complexity,
or other design considerations. For example, in some approaches gain or
antenna beam pattern may be directed toward high directionality to allow
communication between two locations at relatively low power. This may
reduce the likelihood of third party detection or reduce power
consumption in some applications.

[0214]For example, in one embodiment of the receiving optical antenna
assembly, optical antenna elements may be formed directly atop a
semiconductor wafer. In one approach, a portion of the electronic
circuitry or portions of the antenna assembly may be formed integral to
the semiconductor wafer.

[0215]In one embodiment, a plurality of optical antenna elements may be
are arranged to form a pattern that is generally in the shape of an
annular ring, which may be generally circular or another shape. In one
embodiment, the annular ring generally follows the periphery of at least
a portion of the chip. In such a configuration some portion of the
control circuitry or other portions of the antenna assembly, such as
phase adjusters, mixers, or combiners, that is associated with the
antenna elements is partially or wholly surrounded by the annular ring.
The effective diameter or other cross sectional dimension of the annular
ring thereby defines the effective aperture of the optical antenna
elements.

[0216]Regularly shaped arrays are not limited to N×N squares or
M×N or N×N rectangular arrangements. Moreover, the
arrangements are not limited to circular rings, squares, or rectangles. A
variety of arrangements may be developed according to antenna design
principles in a variety of two-dimensional or three dimensional
configurations.

[0217]For example, certain embodiments of patterns of optical antenna
assemblies include, but are not limited to, sets of optical antenna
elements as arranged as an extended dipole, a sinusoidal shape, a
repeatable curve, annular rings, or other mathematically or otherwise
analytically definable arrays.

[0218]Other embodiments of optical antenna assembly configurations
include, but are not limited to, non-repeatable curves, portions of the
optical antenna assembly formed on different layers, portions of the
optical at the assembly at different elevations (e.g., on a non-level
layer), curved or U-shaped structures, discontinuous portions of optical
antenna assemblies that form capacitive, inductive, or matching
structures, etc.

[0219]Moreover, the optical antenna elements are not necessarily limited
to positioning on a single level and patterns may subtend more than one
level. For example, the optical antenna elements may be arranged on
different layers of substrate or may be distributed irregularly in depth.

[0220]As described previously, FIG. 17 shows one example of an array of
optical antenna elements 102 arranged in non-regular pattern. The number
of optical antenna elements forming the ring may range from one pair to a
large number (tens, hundreds, thousands, or more), depending upon various
design considerations, such as power, resolution, cost, size,
manufacturability, or other factors. The layouts of the optical antenna
elements 102 as described with respect to FIGS. 17 to 19 may be intended
to be configured as either receiving or generating optical antenna
elements or element that may both generate and receive, as described with
respect to FIGS. 1 and 2.

[0221]The diameter of the ring approximates the effective aperture of each
optical antenna assembly 100. Circuitry or other elements may be located
adjacent to or integral with the respective optical antenna elements in
some configurations. However, in the approach presented in FIG. 17, delay
lines (phasel taps) 1702 link optical antenna elements to an optical
antenna controller 1700. In this embodiment, optical antenna elements
that are oppositely positioned utilize respective pairs of delay lines
1702, though other arrangements may be selected. The delay lines may be
fixed or may have variable delays. In one approach to variable delay, as
presented in this embodiment, each delay line has one or more phasel taps
(e.g., the φ-adjust 104 as described with respect to FIGS. 1 and 2)
that can be switched on or off under control of the central circuitry or
under other control.

[0222]The operation of the optical antenna assembly 100 is controlled by
the optical antenna controller 1700. In one embodiment, each opposed pair
of optical antenna elements can be operated in tandem. The optical
antenna controller 1700 can operate using as many pairs of optical
antenna elements 102 as are desired, from one pair to the number of pairs
of optical antenna elements that can be present in the optical antenna
assembly 100.

[0223]FIG. 18 illustrates another embodiment of the optical antenna
assembly 100 that includes another non-regular pattern of optical antenna
elements 102 in two generally spiral-shaped patterns 1802, 1804. Each
optical antenna element 102 in each spiral-shaped pattern has a
respective distance from a geometric center of the pattern that increases
as the distance along the spiral increases. As represented in FIG. 18,
the distance to each optical antenna element generally increases as one
follows each spiral-shape pattern 1802, 1804 in a counter-clockwise
direction, though other spiral shapes and directions may be appropriate
depending upon the configuration.

[0224]FIG. 19 illustrates yet another embodiment of the optical antenna
assembly 100 that illustrates selectively using sets of antenna elements
to control effective antenna aperture or other characteristics. In this
example, one pair of opposed optical antenna elements 102 can be
connected or operationally coupled by respective conductors 1902 and 1904
to the optical antenna controller 1700. The spacing of this first pair of
opposed optical antenna elements 102 defines a first aperture spacing
1910. Another pair of opposed optical antenna elements 102 are connected
or operationally coupled by respective conductors 1906 and 1908 to the
optical antenna controller 1700. The spacing of the second pair of
opposed optical antenna elements 102 defines a second aperture spacing
1912. The embodiment of optical antenna assembly 100 as described with
respect to FIG. 19 can therefore utilize the first aperture spacing 1910
and/or the second aperture spacing 1912.

[0225]While the number of optical antenna elements, or pairs of opposing
optical antenna elements, shown in the figures, is presented herein as a
one or a few elements or pairs of elements, it is to be understood that
the number and exact configuration of the optical antenna elements within
any particular optical antenna assembly is a design choice, and
variations thereof are within the intended scope of the present
disclosure. In addition, other regular patterns, non-regular patterns, or
mixtures thereof of optical antenna elements to form an array are within
the intended scope with present disclosure.

[0226]FIG. 20 shows one embodiment of the optical antenna controller 1700,
as described above with respect to FIGS. 17, 18, and 19. The optical
antenna controller 1700, whose components are shown in FIG. 3, comprises
a central processing unit (CPU) 2002, memory 2004, circuit portion 2006,
and input output interface (I/O) 2008 that may include a bus (not shown).
The optical antenna controller 1700 can be a general-purpose computer, a
microprocessor, a microcontroller, or any other known suitable type of
computer, controller, or circuitry that can be implemented on hardware,
software, and/or firmware. The CPU 2002 performs the processing and
arithmetic operations for the optical antenna controller 1700. The
optical antenna controller 1700 controls the signal processing,
computational, timing, and other processes associated with generating or
receiving light from the optical antenna assembly 100.

[0227]Certain embodiments of the memory 2004 include random access memory
(RAM) and read only memory (ROM) that together store the computer
programs, operands, desired waveforms, patterns of opposed optical
antenna elements, operators, dimensional values, system operating
temperatures and configurations, and other parameters that control the
optical antenna's operation. The bus provides for digital information
transmissions between CPU 2002, circuit portion 2006, memory 2004, and
I/O 2008. The bus also connects I/O 2008 to the portions of the optical
antenna assembly 100 that either receive digital information from, or
transmit digital information to, though one or more optical antenna
elements 102.

[0228]I/O 2008 provides an interface to control the transmissions of
digital information between each of the components in the optical antenna
controller 1700. I/O 2008 also provides an interface between the
components of the optical antenna controller 1700 and different portions
of the optical antenna assembly 100. The circuit portion 2006 comprises
all of the other user interface devices (such as display and keyboard).
In another embodiment, the optical antenna controller 1700 can be
constructed as a specific-purpose computer such as an
application-specific integrated circuit (ASIC), a microprocessor, a
microcomputer, or the like.

[0229]In one embodiment, multiple layers of the optical antenna assembly
are also provided. The layers may be substantial copies of each other or
may have differing configurations, spacing, properties, or other
features. In another embodiment, the effective width of the annular ring
of the optical antenna elements can be adjusted by adjusting the number
of active optical antenna elements that can be contained in each row, or
alternatively by activating or deactivating certain ones of multiple
annular rings of the optical antenna elements.

[0230]The optical antenna controller 1700, as described with respect to
FIGS. 17, 18, 19, and 20 can be configured to activate or deactivate
certain ones of the optical antenna elements. As such, the configuration
and element density of the array of optical antenna elements 102 within
the optical antenna assembly 100 can be controlled extremely quickly by
some programming of the optical antenna controller 1700. Replication of
certain ones of the optical antenna elements or redundancy may also
provide fault tolerance, compensate for physical imperfections, reduce
effects of contaminants, such as dust or dirt, add wavelength
selectivity, or provide other design freedoms.

[0231]Reflective, refractive, phase delay, diffractive and/or other
optical techniques may be combined with the optical antenna assembly and
approaches described herein. For example, refractive lenses may be
positioned to provide a curvature to waves arriving at the array of
optical antenna elements or a wavelength selective filter may reduce
light at certain wavelengths to augment wavelength selectivity of the
optical antenna assembly.

[0232]In certain embodiments, it may be desired to provide a scratch-proof
coating above one, or an array of, the optical antenna elements to
protect and ensure the continued operation of the optical antenna
elements. A coating of a suitable covering material such as artificial
sapphire, silicon, or diamond can be deposited or otherwise positioned
above a any portion of, or substantially all of, the array of optical
antenna elements. In some applications, a coating, such as diamond, may
be provided over both sides while providing continued optical antenna
element operation. In certain embodiments, control circuitry or other
circuitry may be integral to or positioned in close proximity to the
antenna assembly, and subsequently protected by such coating. The
concepts of the coating can be sufficiently straight-forward and
self-explanatory and are not displayed in any figure.

Examples of Applications

[0233]An optical system 250, shown diagrammatically in FIG. 21 includes
both a generating optical antenna assembly 100a, which may be the same as
that described with respect to FIG. 2, that provides illumination to an
object 252. Additionally, the embodiment may include a receiving optical
antenna assembly 100b, such as that described with respect to FIG. 1,
that can capture light that is reflected from the surface of the
illuminated object 252. As represented diagrammatically in the optical
system 250, light generated from a generating optical antenna element
102a illuminates an object 252. A second optical antenna element 102b
then captures a portion of light reflected from the object. One skilled
in the art will recognize that the diagrammatic representation of FIG. 21
is a simplified representation of illumination and capture light from the
environment and that the light striking the object will typically be a
function of light emitted from more than one optical antenna element.
Similarly, in some applications, each optical antenna element 102a, 102b
may operate as both a signal generator and a signal receiver. The
simplified representation is presented herein for clarity of
presentation.

[0234]Where the generating optical antenna assembly 100a is configured to
concentrate optical energy or direct optical energy toward one or more
regions, as described previously, the optical antenna assembly can
selectively illuminate one or more spatial locations or angular ranges.
Similarly, in one embodiment, the receiving optical antenna assembly 100b
can receive light selectively from one or more regions or angular ranges.
In some approaches, a single optical antenna assembly may be configured
to selectively direct optical energy to and receive optical energy from
selected spatial locations or angular ranges.

[0235]In one embodiment, a combined illumination and reception technique
using the optical antenna assemblies can be configured to operate
similarly to an optical range finder or LIDAR type of system.

[0236]In some cases, the selectivity, gain, or other operational aspects
may be adjusted by selective polarization or by adding additional optical
structures, such as diffractive elements, lenses, or other known optical
components. While the above embodiment has been described in many cases
as a coherent system, in some cases, an optical antenna assembly can be
adapted to operate with non-coherent or only partially coherent light
energy.

[0237]Often, illumination or illuminated imaging in the optical domain is
either broadband (e.g., a camera flash that outputs light to having a
wide mixture of light frequencies such as white light), or narrowband
(i.e. light produced with a laser that has one, or a small number of,
frequencies). In one embodiment, an optical antenna assembly can be
configured to provide or receive light selectively from two, three, or
more wavelength bands. In one approach, the bands may be primary color
bands, such as red, green, and blue wavelengths. A multiband approach,
such as light of the visible and/or near-visible frequencies, can also be
used in various image capture or sensing applications. In each of these
approaches, the antenna element sizes, spacings, orientations, and other
characteristics can be optimized according to design criteria. In some
approaches, sets of antenna elements may be devoted to each wavelength
range.

[0238]While much of the above discussion of exemplary embodiments has
concentrated on light of visible or infrared wavelengths, many of the
methods, principles, structures, and processes herein may be applied at
or extended to other wavelength bands. For example, wavelengths in the
far-infrared and into the millimeter wavelength range may penetrate
materials to depths different from and, in some cases, greater than
visible wavelengths. Such wavelength bands may be chosen for example to
image objects or augment imaging of objects. In one approach, wavelengths
on the order of one or a few millimeters may permit imaging at depths
different from those of visible wavelengths. Similarly, as
photolithographic techniques or other fabrication techniques permit,
ultraviolet implementations may be realized.

Conclusion

[0239]While several embodiments of application for optical antenna
elements have been described in this disclosure, it is emphasized that
these applications are not intended to be limiting in scope. Any device
or application that involves the use of the optical antenna elements, as
described within this disclosure, is within the intended scope of the
present disclosure.

[0240]Different embodiments of the optical antenna elements can be
included in such embodiments of the communication system as
telecommunication systems, computer systems, audio systems, video
systems, teleconferencing systems, and/or hybrid combinations of certain
ones of these systems. The embodiments of the status indicator as
described with respect to this disclosure are intended to be illustrative
in nature, and are not limiting its scope.

[0241]Those having skill in the art will recognize that the state of the
art has progressed to the point where, in many cases, there is little
distinction left between hardware, firmware, and software implementations
of aspects of systems; the use of hardware, firmware, or software is
generally (but not always, in that in certain contexts the choice between
hardware and software can become significant) a design choice
representing cost vs. efficiency tradeoffs. Those having skill in the art
will appreciate that there are various vehicles by which processes and/or
systems and/or other technologies described herein can be effected (e.g.,
hardware, software, and/or firmware), and that the preferred vehicle will
vary with the context in which the processes and/or systems and/or other
technologies are deployed. For example, if an implementer determines that
speed and accuracy are paramount, the implementer may opt for a mainly
hardware and/or firmware vehicle; alternatively, if flexibility is
paramount, the implementer may opt for a mainly software implementation;
or, yet again alternatively, the implementer may opt for some combination
of hardware, software, and/or firmware. Hence, there are several possible
vehicles by which the processes and/or devices and/or other technologies
described herein may be effected, none of which is inherently superior to
the other in that any vehicle to be utilized is a choice dependent upon
the context in which the vehicle will be deployed and the specific
concerns (e.g., speed, flexibility, or predictability) of the
implementer, any of which may vary.

[0242]The foregoing detailed description has set forth various embodiments
of the devices and/or processes via the use of block diagrams,
flowcharts, and/or examples. Insofar as such block diagrams, flowcharts,
and/or examples contain one or more functions and/or operations, it will
be understood by those skilled within the art that each function and/or
operation within such block diagrams, flowcharts, or examples can be
implemented, individually and/or collectively, by a wide range of
hardware, software, firmware, or virtually any combination thereof. In
one embodiment, several portions of the subject matter described herein
may be implemented via Application Specific Integrated Circuits (ASICs),
Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs),
or other integrated formats. However, those skilled in the art will
recognize that some aspects of the embodiments disclosed herein, in whole
or in part, can be equivalently implemented in standard integrated
circuits, as one or more computer programs running on one or more
computers (e.g., as one or more programs running on one or more computer
systems), as one or more programs running on one or more processors
(e.g., as one or more programs running on one or more microprocessors),
as firmware, or as virtually any combination thereof, and that designing
the circuitry and/or writing the code for the software and or firmware
would be well within the skill of one of skill in the art in light of
this disclosure. In addition, those skilled in the art will appreciate
that the mechanisms of the subject matter described herein are capable of
being distributed as a program product in a variety of forms, and that an
illustrative embodiment of the subject matter described herein applies
equally regardless of the particular type of signal bearing media used to
actually carry out the distribution. Examples of a signal bearing media
include, but are not limited to, the following: recordable type media
such as floppy disks, hard disk drives, CD ROMs, digital tape, and
computer memory; and transmission type media such as digital and analog
communication links using TDM or IP based communication links (e.g.,
packet links).

[0243]All of the above U.S. patents, U.S. patent application publications,
U.S. patent applications, foreign patents, foreign patent applications
and non-patent publications referred to in this specification and/or
listed in any Application Data Sheet, are incorporated herein by
reference, in their entireties.

[0244]The herein described aspects depict different components contained
within, or connected with, different other components. It is to be
understood that such depicted architectures are merely exemplary, and
that in fact many other architectures can be implemented which achieve
the same functionality. In a conceptual sense, any arrangement of
components to achieve the same functionality is effectively "associated"
such that the desired functionality is achieved. Hence, any two
components herein combined to achieve a particular functionality can be
seen as "associated with" each other such that the desired functionality
is achieved, irrespective of architectures or intermedial components.
Likewise, any two components so associated can also be viewed as being
"operably connected", or "operably coupled", to each other to achieve the
desired functionality, and any two components capable of being so
associated can also be viewed as being "operably couplable", to each
other to achieve the desired functionality. Specific examples of operably
couplable include but are not limited to physically mateable and/or
physically interacting components structure and/or wirelessly
interactable and/or wirelessly interacting components or structures
and/or logically interacting and/or logically interactable components or
structures and/or electromagnetically interactable and/or
electromagnetically interacting components or structures.

[0245]It is to be understood by those skilled in the art that, in general,
that the terms used in the disclosure, including the drawings and the
appended claims, are generally intended as "open" terms. For example, the
term "including" should be interpreted as "including but not limited to";
the term "having" should be interpreted as "having at least"; and the
term "includes" should be interpreted as "includes, but is not limited
to"; etc. In this disclosure and the appended claims, the terms "a",
"the", and "at least one" are intended to apply inclusively to one or a
plurality of those items.

[0246]Furthermore, in those instances where a convention analogous to "at
least one of A, B, and C, etc." is used, in general such a construction
is intended in the sense one having skill in the art would understand the
convention (e.g., "a system having at least one of A, B, and C" would
include but not be limited to systems that have A alone, B alone, C
alone, A and B together, A and C together, B and C together, and/or A, B,
and C together, etc.). In those instances where a convention analogous to
"at least one of A, B, or C, etc." is used, in general such a
construction is intended in the sense one having skill in the art would
understand the convention (e.g., "a system having at least one of A, B,
or C" would include but not be limited to systems that have A alone, B
alone, C alone, A and B together, A and C together, B and C together,
and/or A, B, and C together, etc.).

[0247]Those skilled in the art will appreciate that the herein-described
specific exemplary processes and/or devices and/or technologies are
representative of more general processes and/or devices and/or
technologies taught elsewhere herein, such as in the claims filed
herewith and/or elsewhere in the present application.

[0248]Within this disclosure, elements that perform similar functions in a
similar way in different embodiments may be provided with the same or
similar numerical reference characters in the figures. The above
disclosure, when taken in combination with the associated figures,
represents a number of embodiments of arrays of optical antenna elements
included in optical antenna assemblies. Other slight modifications from
these disclosed embodiments that are within the scope of the attached
claims are also within the intended scope of the present invention.